The Wilsons have always been easy to drive with tubes, which is why ARC and others have often showed with Wilsons at shows. The Maxxes are no exception despite the low impedance dip- even our amps which are OTLs (not noted for driving low impedances all that well) work just fine on them. The National sales manager at Wilson had our amps for quite a few years.
With a transformer coupled amp, use the 4 ohm taps and keep your speaker cables short in any event, so monoblocks are advised. Balanced inputs are nice (although the VTLs have XLR inputs, they are not balanced so no benefit accrues) if you can pull it off, which would allow you to run longer interconnect cables. If your gear sits between the speakers, this might be a non-issue.
I recommend something around 150 watts as a nice minimum, which should work fine in most rooms. So you have a wide range of amps to look at.