From what I've seen of the health system, they made troopers about twice as durable, so they can generally survive one hit, but go down on the second. This was most likely to offset the smaller squad size, but does not nesecarilly (sic) make it any easier. I would say that twice the endurance but the same amount of actions balances out to where I would dub it about a 6-9 man team in old X-Com depending on squad size. That plus getting out of the rookie uselesness stage quicker.