Yeah, I'm in more or less the same position, though I do get caught off guard here and there; I've raised Gale multiple times already [the D20 Initiative really sets some balance straight; Astarion can roll a 1 and be last to go]. Certain bosses have been amped up *considerably*, but very much manageable thus far. I've just gotten to Act 3 now. Last game I bee-lined straight for Ansur at level 10 with Act 2 gear and got my arse handed to me. Was nothing I could do, I got completely massacred.
If you do die and continue on Custom, you can keep the Honour Ruleset and actually set some things to make it a bit harder [more fair]. So, hidden passive perception rolls, or not seeing the target DC for skill checks and you can increase the resting costs up to 120. I love those additions, but I'm trying to beat it on honour first. But this is the only way to get it, you can't start custom with those rules.