The 31SE is a pretty good step up over the 30SE. Just like the 51SE is much better than the 50SE. Dynamics do improve, you have great preamp with the 31SE.
Why would you want to try other amps? BAT SS and tube amps are wonderful. I've owned VK200, vk60, vk75SE and now VK150SE's...The amp/preamp combos from BAT are hard to beat. I'd get a VK250 and not look back. Maybe buy a 2nd and run them in mono down the road...For just over 4k, you could get 2 VK60's run them in mono if you want high powered tubes....
Why would you want to try other amps? BAT SS and tube amps are wonderful. I've owned VK200, vk60, vk75SE and now VK150SE's...The amp/preamp combos from BAT are hard to beat. I'd get a VK250 and not look back. Maybe buy a 2nd and run them in mono down the road...For just over 4k, you could get 2 VK60's run them in mono if you want high powered tubes....