Not sure if you have much interest in changing BG1 around, but I've been playing it recently with IR and I have a few thoughts...
At the moment IR increases the player's power in BG1 quite a lot. The main thing is the +strength items, of which there are three if you include the belt from Rasaad's quest (I would personally prefer that any EENPC items be relatively weak so I can happily remove them). You can get two characters to near-max strength, plus many items like varscona are straight-up buffed compared to vanilla. In fact, two of the strongest weapon classes (longswords and scimitars) receive considerable buffs, while many "bad" types like axes, flails, katanas, and halberds, remain bad. Missile weapons are a little bit nerfed, but you forget about that pretty quickly when you have a 25-strength level 5 fighter dual wielding varscona and the new and improved vampire's revenge. With so much strength available, dual-wielding is supreme. Generally I am not a fan of the conversion of strength-setting items to +strength items, even in BG2. It favours powergaming or custom parties, since if you have good stats already it makes you even better, and the items can often be combined to reach 25 strength on multiple characters, which is mostly impossible in vanilla. In vanilla these items are a great way to improve suboptimal bioware NPCs, while powergaming is somewhat limited since they can't be stacked.