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

If you would like to keep XA30.8, maybe a high sensitive speaker with powered woofer is a smart move. For example paradigm 9H with sensitivity 93-96db 

I think a key question is how loud you drive your speakers.  Most people are too focused on amplifier power.  Even Nelson Pass seems to agree with this, given his side company First Watt!  If you are not listening at ear piercing levels, I would doubt you need an amp upgrade.

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 :-).

For some reason the link didn't post, but you can find it if you google X250.8 review and look at Terry London's Hometheater review