I apreciate comments about other Gm and players, but i would like to know(therefore i post it in rules forum:)if there is something already officially written about it for the compatibility or rather to have an official moderator opinion of this matter.
I'm more interested about the strict official rules, because if there isn't anything officially writtten or no official response is given to me, i'll give my Gm total free choice about it.
If other peoples wants to share their personal experience with this problem, feel free to comment, if i see sometyhing useful, i can propose some modifications for the spell to make it work better.
*the + 5 bonus cost could work indeed.