Yeah, Spellheart weapons are good if you are using a non-two-handed character. Especially a TWF oriented Dex-heavy character is very good with it. (Daggers that do 5d6). For two-handed characters they do relatively little.
A Greatsword user with 22 Str gets 2d6+9 weapon wise and 5d6 by Spellheart. Thats about the same average damage.
I like the channeling variant, especially as I want to use unseen impetus and its a nice way to circumvent the fact that the normal blast only uses d4s.