I would like some input on which body would offer the better resolution and high ISO performance. I shoot mainly portraits in studio and on location and bands also in studio and live shows. I've narrowed it down to two used bodies. The 5D (original) and the 1Ds mark ii. Thanks for your input!
I've not tried one myself yet, but I have to echo the D700 suggestions. You really should stick with the Nikon brand, and also it just may be that you are shooting part of the time, in available light? But it sort of depends on how many Nikon lenses you have, and if you like them...and if they are full frame. You can buy a used D700 for around $1500. I have never seen a photograph taken with one, that I didn't like.
I just don't like the ergonomics of Nikon's full frame bodies. I need fingers that are 6 inches long, to reach the shutter release. And the controls on the rear, are way too tiny.
Regarding the image size issue, I don't see it as one for the type of work you do, unless as mentioned above, most of your work winds up being prints that are 20x30 or larger.
I've wanted to try Perfect Resize, myself. I like Photoshop's standard "bicubic" enlargement ok, but it's far from..."perfect". The "bicubic softer"...supposedly "best" for enlargements...really seems best for making a picture soft and ruining it.