I did not mean to be rude or abusive by stating my opinion on one facet of your work; on the contrary, I think the system as a whole is great for helping out martial characters. However I air these complaints because I believe that this discussion could make the system even better than it already is now. It certainly does increases the power and versatility of martial characters, just as Spheres of Power reigned in the infinite versatility of spellcasters. However, in my view of a ideal game, there should be as little difference between the capabilities of a martial character and a caster character as possible. And while the two systems have certainly made huge steps in the balancing between martial and caster, I don't think we can reasonably say that SoM martials are yet equivalent to SoP casters in terms of power or versatility.
The easiest way to prove this, is to simply look at the number of SoM Legendary Talents that are effectively replicated with SoP Base Spheres. If I want to raise an undead army, I could grab the Warleader Sphere and then take the Legendary Talent, Armies of the Dead, which has a BAB +6 prerequisite. Even then, I have to succeed on a Diplomacy check to raise the undead's attitude all the way to friendly, and all of that assumes that undead are even around for me to use Diplomacy with in the first place. Compare that to any Spheres of Power caster, who can simply take the Death Sphere. Sure there are limitations to the undead you create (mainly longevity), but the character concept of a necromancer is still functional. You can always simply animate dead as needed, whatever undead you want, without having to ask the GM for permission, and without having to hope that the GM throws non-hostile undead at you to use diplomacy on in the first place (this Legendary talent would probably work a lot better if it worked on the defeated corpses of your enemies and then raised them, IMHO).
Let's also take a look at two of the other things you mentioned, Teleportation & Flight. Teleportation is a Legendary Talent from the Beserker Sphere, Rift Strike. It's functionally equivalent to the Advanced Talent from the Warp Sphere, True Teleport. This is great! But it's limited specifically to going from location A to B. If I want to be the guy who teleports around in combat, in a manner similar to Dimensional dervish, then I'm better served just taking the base Warp Sphere, which gives me access to short range teleportation from as early as level 1. Then there's Sparrow's Path, a Legendary Talent from the Athlethics Sphere that enables you to fly, albeit in a somewhat limited manner until level 8 or so. But in Spheres of Power, I could just as easily grab the Alteration Sphere as well as Elemental Transformation, and have access to a fly speed, a swim speed and a burrow speed all from first level, and all superior movement modes to what's available to an equivalent level Spheres of Might character, again without having to beg the GM to allow Legendary/Advanced Talents.
So when we compare the two systems directly, it's pretty clear which system has more "power." And this is before getting into stuff like the Life Sphere, for which there is no direct analogue in Spheres of Might. With this in mind, I have no idea how you can write off the abilities one obtains from Spheres of Power as "being worth a trait" and then directly say that the abilities one gains from Spheres of Might as "being worth a feat, or more." I fear there's a major disconnect in opinion here if this is true. That's not to say the SoM stuff isn't worth more than feat (one would hope so, IMHO), only that I think you may be drastically underselling Spheres of Power.
But getting back to the main point, I guess the issue from my point of view, is that Spheres of Power is already a stronger system than Spheres of Might. Or at least that's what I believe by directly comparing the two. Thus it's especially jarring to me that Spheres of Might is loosing out on the versatility of the Sphere Drawbacks. In Spheres of Power, if I didn't want a particular ability, there was always a drawback I could choose to get rid of it. But here, if I don't want a particular ability, my only choice to take the ability I don't want, or take another ability that I still may not want. Either way, it makes character creation more of a grab bag and less of a customization. It also differentiates my character less from other similar characters, since you can be sure that anyone who takes a sphere will definitely have either X ability, or Y ability. I can't help but feel that this subtracts from the system.
And sure, each talent in SoM may grant you a new ability. But if all of the abilities are balanced against each other, then why does it matter if I get an ability I choose for myself or an ability that is already chosen for me? The idea of pre-chosen talents as a balancing tool really only makes sense if you admit that you are purposely choosing substandard talents for those drawbacks. But then, why would you have substandard talents in the first place? If substandard talents were created just as drawback fodder, then it would be easier to just not have drawbacks at all, and save on word count. Of course, I doubt that this conspiracy theory tangent is the actual case here. I'm sure you have access to tons of playtest data that I don't have, but if there was a problem wherein the presence of drawbacks somehow led to an abuse of the system, then please tell us specifically so we can better understand the reasoning for this decision and have a more productive discussion on how to move forward. Without that reasoning, it simply seems like an arbitrary way to limit player choice and freedom in order to preemptively solve a problem that many don't even know/think exists.
Once more, I'd like to reiterate my love for both the Spheres of Power and Spheres of Might systems. I'm not complaining because I hate the system or it's developers. My only intention in writing out these long posts is to help the system be even better than it currently is. Drawbacks were one of my favorite things about the original Spheres of Power. Hearing that the current plan is to eliminate all player choice and variability from them is...disappointing, to say the least.