Steve,
I was in your position about four months ago. I could not decide between the Jet 1642 and the Nova 1624. Three major factors played into my decision to puchase the Nova 1624:
1. My shop has a very limited amout of space. I operate in a rather small section of the garage between my wifes car, and 48 years of crap she has hoarded.
2. I am not a woodworker, so I never plan to turn any long spindles. If that changes in the future, I can always get a bed extension.
3. Not true for all lathes, of course, but my experince with variable speed has been a lack of torque. I can run my Nova at its lowest speed, push my biggest gouge in as hard as I can, and the lathe will not stall.
I love my Nova 1624-44, and have not regretted my decison for 1 second. It is very easy to change speed by moving the belt, and it is a VERY high quality, well built machine. I also saved enough money to buy a chuck and a Tormek clone from Grizzly. If at some time in the future I decide that I need the variable speed, my choice will be very simple: DVR XP. Maybe someday I will be able to afford a mustard monster or mayonaise beast, but for now, my Nova does everything I ask and much more.
The most amazing thing about the Nova (I upgraded from a Palmgen/Craftsman 15" reeves drive lathe) is that the quality of my turning has improved exponentially!!! I give the Nova 5 stars, and I'm sure you would too if you make that choice.
Good Luck,
Dan