Well, for us there probably isn't any benefit from the steering feel/responsiveness from EPAS as we can't really change drive modes. So from a performance standpoint it supposedly steers the same as the hydraulic unit.
For me, the winning notion was the idea of getting rid of the hydraulic aspect. I can now drop the pump, reservoir, lines and cooler, saving the weight, heat, belt drag and mess. So basically it's giving me the same steering with better implementation. I certainly don't have the experience/know-how to build a steering strategy, but I suppose it's possible that someone could make a tuning selection box (kinda like a pedal assist or boost dial) to talk to the EPAS, but this swap has been around for at least a couple years now and I haven't seen anything. That probably says it.
As for o-rings, years ago I decided to bite the bullet and get a few "master" sets of various types of o-rings. Cost me about that much for each set, but in the last 8-9 years I think I've had to buy maybe one o-ring, between the cars, bike, mowers, HVAC, etc. O-rings are kinda like plastic push pins and shrink wrap...5 for $9.99 or you can get 100 for $5 at a supplier. I always get a kick out of seeing shrink-tubing at the store. Those little bags of a couple pieces for stupid prices. I have 100ft reels of the stuff from 1/8th to 1.5in I think I paid maybe $12 each for.