I have a Sansui DVD-VCR combo. Before we get into the technical things, I should tell you that Customer Service for Sansui SUCKS so when you have problems with the machine, you'll be teaching yourself how to solve them rather often (which isn't necessarily a bad thing).
A few things you have to know: Dust is a problem, and even with a CD laser cleaner, you can still have problems with dust, so a can of compressed air is also a good idea.
If you've got everything you want on your DVD and you're done burning it, make sure to finalize! My owner's manual didn't exactly make it clear that there's a connection between finalizing the disc and playing it in seperate machines, so I took it to be an optional step initially.
As far as shopping for a machine goes, I guess the kind you want depends on how much fun you want to have, so if you were looking forward to making your own menu designs and that kind of thing, forget the Sansui.
And a word of warning, I've learned from friends that this isn't a problem restricted to just my machine---the burner can be flightly with video quality sometimes. As a general rule, if it's bad VQ it won't burn, but sometimes the stars are aligned right and a bad VQ tape will burn, and on the other hand, a tape with pristine VQ will refuse to burn. Just one of those things. This problem is more infrequent if you use wires to hook up another VCR and record off that instead of the one in the actual console, so this sounds like weird advice, but even if you buy a DVD-VCR combo, hang onto the old VCR and hook the two together just in case.
Burning modes are the same as VCR mode, SLP, LP, and SP (and on the Sansui, XP, which is one hour of recording). SLP is the only mode that is "noticable" (the things I have burned in SLP look like something in WMP being played on full screen; quality is still very good and watchable, that's just what it looks like). LP (4 hours) is the best mode possible because it'll hold ten commercial-free shows, and the difference between it and SP is negligible at worst (i.e. little things like pixelations on the edges on things will sometimes happen, but nothing that makes you rip it out of the machine and say "THIS SUCKS, MA!")
Another warning is that on the Sansui, tracking can't be fixed after burning starts, so check the tracking before you hit the all-important button.
I'm not really a tech-head, so this is all the advice I can give, but I hope it helps before and after you make your purchase.