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

I have intimate experience with both the XA-30.5 and the X-250.5 as our main stereo amplifier.
Our system, at the time, was:
Wilson Watt Puppy Va speakers, Meridian 800 transport, 861v6 processor, MIT Oracle Max2 Balanced interconnects, MIT Oracle MAX speaker cables, MIT Oracle MA Digital interconnect, Sound Application RLS power conditioner, CH Acoustic X-20 power cords, a single Pass XA-30.5 (for stereo) and 3 X-250.5 amplifiers (for theater). 
We now have 3 Pass X-250.5 amplifiers for theater and a pair of XA-200.5's for our integrated stereo system. Currently using Sasha I's, our setup emphasizes stereo over theater.
I state our system so one can realize it's level, which can easily reveal the character of system changes, recorded quality and the acoustic of the recorded venue.
For a long time, we listened to the XA-30.5 as our primary stereo amplifier. The X-250.5 wasn't a match. While the 250.5 had better bass, and (as Kent English and Mark from Reno HiFi state) was "faster," the 30.5 was dramatically more coherent. The sound stage and imaging were much better defined / fleshed out, coherent and much more believable. We were able to easily define the acousitc venue and the performers subtle cues and expressions. EVERYONE who heard the comparison easily picked the XA-30.5 as their preference.
When we were selling one of our X-250.5 amplifiers, I was concerned the buyer would want to hear the XA-30.5 because they would have changed their mind!
I'm a educated and licensed Chemical Engineer, and I learned a long time ago to hear and listen to equipment before making any assumptions or "educated" presumptions.
I believe the XA-30.5 is one of the BEST bargains available! It operates in class A up to 30 watts and puts out just over 200 watts in class AB. Perfect - no but what performance for it's price.
Just my experiences for your thoughts.
I have yet to hear an XA- .8 amplifier. Maybe one day we'll get an XS amplifier :-).

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 . . . 

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 :-)

Will - we also use a high end power conditioner and some of the best power cords available. Clean power transforms a system's performance - highly recommended.

Our Sound Application RLS power conditioner feeds our front end components (Meridian 800, 861v8, 621, Oppo 205) via CH Acoustic X20 power cords. This creates a very noticeable improvement.
Our Pass amplifiers are plugged directly into dedicated 20 amp circuits with CH Acoustic X20 power cords. Plugging our Pass amplifiers into our power conditioner has the least improvement and we leave them plugged into their own dedicated 20 amp circuit. This, I believe is because the Pass amplifiers have a very well regulated & filtered power supply,