About the Absolute Towers and the Classic 4's. First off, there has been a lot of discussion earlier in the thread comparing the Threes and AT's with some preferring one over the other for different reasons. I did my own comparisons as I had set up a close friends system using AT's (compared them in my room first).
As for the Threes and AT's, I prefer the Threes while others feel they are too 'analytic' I prefer the midrange of the Threes to the Fours, which seem a bit 'softer' to me. This may be due to the difference of the Threes having all metal drivers and the AT's having polypropylene drivers (except for the tweeter). The lower XO for the midrange for the AT's is at 450Hz and 800 HZ for the Threes, also accounting for differences. Now, for HT purposes, the AT's will play louder (has more piston area) than the threes with the same amount of power applied, even though on paper they have the same sensitivity (close enough). The Threes will dig deeper but that's a moot point when you XO at 80 Hz.
Now as for the Fours, they are actually a different beast. Even though the top portion Fours 'look' just like the Threes with a bass driver added, it's not so. The midrange sound is quite a bit different and I prefer the Fours. Jack Hidley, who was one of the designers of the Classic series, confirmed this much earlier in the thread. The 6.5" driver for the Threes is made to play in the lower octaves while the one in the Fours is not- it's a 'Lower Midrange" driver and is XO'd to the woofer at 125Hz. The Fours will play louder and very deep (with room gain, it easily is flat in my room to 25Hz. Do I use it 'Full Range"? No, I do not, I XO the Fours at 60 Hz to the subs. Keep in mind that the best place for speaker placement (imaging) is not the best place for bass (subwoofers) in just about all rooms. Having the Fours XO'd at the higher freq does give it incredible dynamic range with no strain.
So, IMO, the Fours are much better than the AT's, but between the AT's and Threes - it's really a preference. Keep in mind though, the Fours are HEAVY and large (twice as deep as the AT's) - they are 16" deep compared to the AT's 7.25". If size is a concern, you may want to look at this. They both look great, as all the Classic series do (as long as you like piano high gloss black). If I had the room, I'd love to have Fours all the way around. But as most folks here, we have limits to room and budget concerns.
Can you go wrong with either choice, not really. I can easily live with either one, even though I prefer the Fours. Sorry, that probably does not help in your choice. It would be great if you could listen to them first. I've been lucky that I've had friends and family that purchased NHT (on my recommendation) and have set up their systems so can do a lot of comparisons as I like to test the equipment in my room first before setting it up elsewhere. Am I a 'fanboy', not really. I like a lot of other speakers also and have different brands in different rooms in our house. I do think though that NHT still represents very good value for the buck (they sound great, have a great finish, and are built well from a company I respect). There is other great competition though (such as SVS Ultra Towers which have similar specs and finish), also a company I have great respect for (and there are others). I've owned NHT's since the introduction of the original Super Zeros in the 80's (along with speakers from JBL, Infinity, Pinnacle, Fosgate Audionics, Energy, Boston Acoustics, Velodyne, B&W, Parasound, and a few others). I've still stuck with the NHTs...
Good luck in your decision.