In fact, I am playing IWD Complete (GOG version), without SCS, right now. Playing on Core rules, with a very suboptimal party, because I wanted to go in without meta knowledge beyond some general information about AD&D. I even made the silly mistake to make an elf enchanter in the party. Now I have a squishy character who costs me 7400 gold to revive if she accidentally dies (which has happened twice), and plus - she can't memorize to use Fireball, Magic Missle, etc., can only cast them from a scroll. I am not dual/multiclassing anyone. I also made a pretty suboptimal druid, with way too low strength and dexterity.
Your claim about PoE's combat encounter design being better is so utterly ridiculous that I'm not going to waste irony on it. I doubt there will be a single person on this forum to agree with it, even the biggest PoE fanboys. Since my memories are fresh, I can cite a long list of set piece encounters in IWD which have no counterpart in PoE. I don't know what's your experience with PoE. I'm playing it since the beta and I don't deny that combat has improved since the "1.0" release version, with the reduced trash mobs and the additions of AI, which the game simply
didn't have at release, and I'm talking about enemies, not just about party AI. Even with those fixes, PoE is miles off from IWD specifically in terms of encounter design. As a known diehard fan of IWD,
Sensuki can talk in more detail than I could off the top of my head.
Regarding combat feel, as I've said myself, it's my opinion, because this is a more subjective topic. I think PoE combat is objectively harder to read than IE combat, but if someone claims the opposite, I can't really do anything to dissuade them.