Isocab, mini-amp recording question!

[Sonixx]

...However, I need to keep the noise down...

what do you mean here?

I'm looking for any insight into this, specifically the difference between a hard driven 8" speaker (as in small combo amps) vs. a 12" speaker.

I'm not sure you can draw any hard and fast conclusions that are universal.

with that said, here's a HT-5 Combo 5W driving the stock 10" open back cab and driving V30 in a Mesa cab. The only thing I'd take away from the clip is the 10" can sound pretty good.