I've used the PGA ADIG for long time, I do know that Alex Flouros still uses his for recording (simul with a cab, the Palmer to add bottom end punch interestingly). I needed something for silent recording and amptweaking.
Of course as a load its cool, you don't need to hook a cab to it, it can be tweaked to sound "good", although it of course still sounds "direct". I found it very useful to add (in parallel, with a mixer) a cheapo Lexicon MPX 110 set to Ambience for a bit more natural sound . . .
Compared to other products (I'm familiar with most of them) I think its esp. nice when used in combination with something like the SE-100 or even a PDI09 (no load, just sim), which are voiced a bit different to get less of that typical directness.