1 meg of chip is more than plenty for image viewing. I used a DCTV with my A500 with 1 meg chip for years without any problems.
I got a DCTV for my A1000 recently after seeing clusteruk's vid on his A1000 with a DCTV, displaying PICs and VIDs.
So, my guess is, if you are an end-user just wanting to disply things (or maybe some basic conversion / rendering), even 512k CHIP will be OK..
I do agree a second monitor is nice to have with the DCTV or RGB/composite button on a A1084 works well.
That was something that confused me when I got my DCTV. I thought it was broken.
I couldn't see any DCTV images on my monitor normally.
(I didn't get any manuals with it, and I still haven't found any scanned ones online)
THEN I found out that it outputs DCTV images via it's composite output, not RGB. So, I couldn't do some of those things without a second monitor or RGB/composite switch on the 1084...
Luckily I was able to acquire a DCTV RGB converter not too long ago, so I can see that flower pic in 24bit color. ;-)
I haven't tried any digitizing on my DCTV / A1000 yet as I still haven't made my parallel port adapter. (The A1000 parallel port is wired a bit different.. I didn't know that before I got my 1000...)
desiv
p.s. I had a HAM-E for my Amiga 500 (512k CHIP) back in the day, but it was RGB only (well, it might have worked with a GENLOCK??? Never tried).