Went and listened at my local dealer. They had a demo MKI and a new out of the box MKII. They were both energized for at least 4 hours... The MKII did better bass definition, more holographic sound stage, better image placement, more dynamic, lower noise floor, and a more relaxed / natural presentation. Whether this is better than some good NOS tubes -- maybe. I can tell you the LS25MKII sounds much more like the REF2 than ever before. In fact, based on what I heard, I would not consider paying 5K more for a REF2. I spent a significant amount of time with the dealer, since they are also friends. We had beers and spent about 8 hours of listening to various types of music. I am not sure of the actual circuit topology changes, some say ARC was having issues with 6922s, others say the 6L6 topology is better musically, and others say it is the influence of the newer designers. I am personally making the choice to send my pre-amp in after the holidays, when I can borrow another during the 3 week wait. Your best bet is to borrow a MKII (if you can) and see if it is better for you. The other cool thing is 12V triggers to control amplifiers and other devices with the capability. The VT100MKIII is also out and has the triggers and new circuits... We listened to the pre-amps with VT100MKIII and the VTM-200s on Proac Response 5s with AQ Anaconda XLRs and AQ Everest speaker cables, equipment residing on Zoethecus stands. All of the same cabling was used for the equipment swaps, stock power cords were in use.
