Ditto, Mezzanine, on the loudspeakers! As to these specific suggestions: If you get the ProAcs or Vandys at the right price, you shouldn't have any problem at all reselling, if for some reason they don't suit your own situation. For Zu, please do read the Audiogon forum responses thoroughly -- there are many close observations on their sonic characteristics, plus useful comparisons here.
You may also find that more sensitive, tube-friendly loudspeakers "wake up" at lower a volume and have a bit more life at civilized levels. For me personally, I tend to have little interest in models that won't show well with something like 9-10 watts Class A EL-84 power, even if you don't go there amp-wise for your own circumstances. There are exceptions, of course.
And don't overlook the fact that Paul Speltz's 'Zero Autoformers' will let you optimize the power output of tube amps of modest power, or the First Watt amps for that matter, into loudspeakers having an impedance minimum right there in the midrange where you may need EFFECTIVE power the most! They are not just for the OTL guys -- see Paul's website for plenty more on this. I keep a set of these around for exactly that reason. A First watt J2, being one example many may not have considered in this respect, should simply put more watts into typical examples of these loudspeakers, according to the math. This is because you are current limited -- it's similar with small tube amps which are not optimized for low-distortion power into low impedances, like some of the small Decware amps are. Nelson implies -- you may know how the Zenmaster operates with respect to pronouncements of opinion -- in a recent addition to the website something to this effect.