We have a customer who's looking for a new webhost, and has some key web dev personnel who use "older" browsers (e.g. IE5 and earlier). Which control panels will be partially or totally unuseable by this requirement? Which specific features?

I've spent some time surfing several of the main vendors, but it's very difficult to find out which specific features won't work. Tools/features with workarounds aren't a big issue (i.e. much file management can be done via FTP).

Pointers to cp reviews that touch on this, would also be appreciated.