I'm largely in agreement with most of the above. However, I keep going back in my mind to low tech = minimum maint and high tech = higher maint. There are likely counter arguments I haven't thought up yet, but in general, to me, other than food, if you have to add something to the tank more than once a week (either manual or automated), it's high tech. If you don't, it's low. In addition, if you really should be pruning your tank more than once a month, it's high. If not, it's low.
So, to me it's more a question of maint levels.
I've got my higher end 46g where I add daily ferts, do 50% weekly WCs and prune 3 or so times a month. I've also got a 10g with a internal filter, a 27w cf desk lamp and Eco substrate (I figured it couldn't hurt). If I get around to changing water every 8-10 weeks I'm doing good. Certainly not optimal for the inhabitants (fish (low load) or fauna), but the tank continues to look pretty decent and growth is apparanent.
So, what did I miss

?
Brian.