Easier maintenance ARCVT100mkII or VTL mb125

Do not know about the VTL MB125, however, the ARC VT100MKII can be tricky and expensive to re-tube. Try
http://mycollins.net/audio/ He goes through the re-tubing procedure for the ARC. (Nice detailed pictures) Last time I checked with ARC, the cost to retube the 100MKII was in the $800-$1000 range plus freight.

I can't comment on the ARC or VTL. But, you can get autobias tube amps. Wolcott's and BAT are 2 examples...

Ease of maintenance led me to the BAT VK-60 with autobiasing. No need to mess with meters and small tools.

The expense and hassle of ARC Tube amps caused me to switch some time ago. Except for the latest model, biasing them was a PITA (for me anyway). There are a lot of amps which allow bias of each tube individually using either an LED or a meter (built in or otherwise). These are easy to use and for the most part allow you to replace individual tubes with like kind and quality with out the need for matching. Auto bias is convenient but not necessary.

Customer usually has to adjust bias because playing around NOS tubes(especially those unproved sources). Standard 6550 on ARC usually don't create problem, I used to own ARC VT100II and classic 120 for total of 6 years(no problems). I am not sure how much freedom you can try differnt tubes on auto-adjusted ones. Also, another Agoner posted before thought his BAT-60 has shorter service life time than his ARC classic 150. I never need services for bias on ARC's amp while owning them(maybe my ears are not golden ones). Once dial-in with reliable tube sources, they are stable. If you play around with differnt tubes, I guess you must be a tweak guys and should not be bothered to rebias them. Some friends have to constantly adjust his tube amps(not to mention the brand), and that's pain!