I can only speak for myself, but even if you have those "overpowered" items, you will get your ass handed to you more than once if you do a tactical SCS I+II install.
I don't think so - DavidW said that SCS/II is designed for the 'standard' BG2, rather than for a game with all overpowered item mods ever created.
Yep:
SCS is balanced with the original game in mind.
Having said that, difficulty is very player-relative.
SCS, ultimately, is scaled to me: i.e., I find the game about the right difficulty with
SCS installed, on Core difficulty, and with no item-enhancing mods installed. (And I think I'm a reasonable but not outstanding tactical player, who's been through the game about three times and who knows the
AD&D system pretty well but isn't all that on top of the detailed ways to optimise a
BG2 runthrough.) It's too easy for some people. It's too hard for others (by which I mean: too hard for playing
BG2 to be fun, not necessarily too hard to be completed full stop.) So maybe there are people out there who want
SCS AI (maybe because they dislike stupid behaviour) but then also want overpowered weapons to bring the difficulty down. That's fine with me.