Upgrade from Pass Labs XA30.8 to X250.8. Worth it?

Will - regarding the 200.5's compared to the 30.5's, I asked the same question to Kent English and he chuckled and said, at one time - the 200.5's were the best amplifier we knew how to build so yes they are significantly better than our introduction XA line 30.5 amplifier. Of course, he was correct.
Summarized, the 200.5's do everything very well.
Different people are sensitive to different things. I remember consulting with an audiophile here on Audiogon when considering the Lamm 1.2 monoblocks. After hearing them on an almost identical system to our own, I realized the are slightly bass heavy. After reading more on the recommendation, I learned the person recommending the 1.2's was a bass player.
The same is true for video - something that may be very objectionable to one individual (black levels to me) might not even be an issue to another individual.
For me, creating the illusion of a live performance in our listening area is everything. Because our set up is not in a large room / hall, I prefer small acoustic venue performances. Our system is pretty convincing. Here, the 200.5's have a natural acoustic that recreates the performers, the acoustic venue and their own performance convincingly with little, if any weaknesses.
I also listened to Spectral amplifiers (when I listened to the Lamm 1.2's) and the Spectral were a little dry - that is they didn't have the same natural acoustic of a real performance the 200.5's did.
Similar but being super critical, were Dan D'Agostino's Momentum monos. They're the closest (I've ever heard) to the Pass 200.5's but were just a slight bit shy of the natural acoustic of a real performance. Does this matter, well - at this level and cost of equipment - to me - yes. (I've read the Momentum's bass betters the 200.8's but the bass wasn't as critical to me)
All this is just my opinion and what I prefer. You may have different tastes. Ultimately, for me - it's all about re-creating a live performance in our listening area. Our system does that amazingly well, we've tested it with our son playing his sax in our listening room and then playing some David Sanborn (not an audiophile recording). The acoustics are almost indistunishable - almost! Now, if our son could play like David Sanborn . . . 

I live not far from the Tekton Design home office. I went in today to have a listen to the Double Impact speakers. At first listen, these were incredibly detailed speakers that had most of the improvements I was hoping for in an amplifier upgrade. 

I think my next purchase will be from Tekton. I’ll revisit the amplifier question a bit later. 

@tjassoc I’ve read your last post a few times. I’d love to get my hands on a set of 200.5’s. Every review I’ve read makes me think those are THE amps to own. Perhaps even over the 200.8’s. Thanks for the insights.

Will - enjoying music is what it's all about.
whitecamaross has a LONG amplifier review post going. It also includes pre-amp's and speakers. He's reviewed the 200.5's and was supposed to review the 200.8's but the transaction was canceled. He hasn't posted in a while but I'm confident he'll continue his record setting review thread.
Glad to share - good luck and happy listening :-)