I play on ACR Poker but mostly SnGs and tournaments, so I cant give you detailed advice about this. But as Station_Master say, the jump in skill level is usually quite big between 10NL and 25NL. I can also fully confirm, that regular tables tend to be softer, especially if you table select a bit. That is/was certainly the case on pokerstars, where I have played most of my cash game hands years ago. On ACR Poker you can table select by leaving tables, where you only find regs. And since you use PT4 already, this should be a familiar process to you. Best of luck
For what its worth, I have recently played a bit of 25NL regular tables on ACR Poker, and I think, they are not all that tough. Certainly something, which I feel, a player solidly winning at 10NL should be able to beat. So I think, the main issue for OP is the BLITZ format and not the transition from 10NL to 25NL. Even having been away from cash games for 5+ years, I would not bother to begin any lower than 25NL, if I was to decide to go that way on ACR Poker.
The issue is most likely going from reg to blitz--speed tables have a completely different strategy dynamic as the V play top of range hands and just fold until they get those hands. It is difficult to beat the rake at low stakes blitz because of the above type of play. You also cannot target weaker players as easily. If you want to move to 25nl stay reg table and table select