I previously owned Model II, MkII's and Lotus SE's, I did hear the IV's and V's quite extensively. The Model 2 is pretty similar, used the same midrange speaker and tweeter. My biggest problem with the Alons was trying to get a continuous, coherent sound. IMO the woofers were warmer than the mids and highs, ie. whenever I got the mids and highs to where I liked them, I would get woofer boom. The IV's are even more difficult, the II's and V's were often preferred because their 10" woofer was a little more tight and articulate than the 12" in the IV.
Having said that, perhaps you can get better coherence out of these than I was ever able to. I think tri wiring is a must with these speakers, using different cables for the woofer vs. the mids and tweeters. I would use something thinnner sounding (perhaps a silver cable) on the woofer and something warm on top. The best cable I ever had on top was Kimber Bifocal XL's, this is too warm for the woofer. I never did find a cable to control the bass to my tastes, YMMV.
As far as placement in the room, the farther away from all walls the better. I actually preferred mine on a long wall placement (the only speaker I ever owned that I preferred this placement). They need to be at least 3',preferably 5' or more from the front wall (actually you cannot get Alons too far out from the front wall), you absolutely do not want any bass reinforcement! They are not terribly picky about side wall placement, at least 18" or so, I just liked them way wide apart, even up to 8' worked for me, again different from any other speaker I owned. Point them straight ahead as Alon recommends, toe in creates incoherence, excess of mids and highs in the mix.
As BigKidz mentioned, they do like tubes, EL 34's for the mids and highs but you'll suffer in the bass, KT88's may be the best all around answer.
If you do end up with problematic bass, you may want to check with Nola for replacement woofers, later series used Alnico woofers, not sure about the 12", however.
