Thanks for all these responses so far. While I understand the mechanical differences between the two models, what I'm really wondering about is how the experience of owning them would differ. In other words, is the Classic motor more likely to break down? To need more daily/weekly/monthly adjustments than the AVL? Are there differences in the types of regular maintenance tasks I would need to perform?
I understand that both models need a fair amount of DIY maintenance -- which is what I want. I was just trying to get an idea of just how much less the AVL might require, which by all accounts doesn't seem to be much less than the Classic (which is fine by me).
Dewjantim's comment on the AVL overheating at low speeds, if true, tells me that the Classic motor might actually be better suited to what the majority of my riding style will be. I live in Brooklyn, NY, where I commute to places in Brooklyn and Manhattan by bicycle just about every day. I'm almost always traveling faster than vehicle traffic (which rarely exceeds 25 mph), and in fact it's quicker for me to bike to any given place than to take public transportation. The motorcycle is more for fun and recreation (and the reward for finishing my dissertation), though it will occasionally be used for practical commuting and traveling to Summer conferences.
And hey, if it's got the romance of drum brakes and a carburator, I can live with that.
I'm curious as to how aesthetically authentic this new unit construction Enfield will be. If it turns out to be a modern fuel injected engine in a G model (or similar) body, as suggested once by Kevin, that would be pretty amazing, but it would also be more "forced," since the G hasn't been in continual production like the Bullet. That's where the Bullet has its authenticity in the face of other brands that simply resurrect or try to approximate a past style for nostalgiac (or marketing) reasons. I can't wait for the reports of the Birmingham bike show this Fall.