err.. how heavy is THAT heavy??! You can pick it up and carry it around your house or whatever, yeah, but I made the mistake of carrying mine across london on public transport one day and it is not something I'm going to do again! Arms ached for about a week afterwards, mainly cos I had to walk about quarter of a mile to the bus stop. I had to put it down and rest every 3 minutes!
The most annoying thing about carrying it is the weight is all on one side, so if you use the handle it's all lop-sided and awkward. Sticking castors under the cab makes life a lot easier.
I'd be interested to know how it sounds through a 15" speaker. Frankly I'm amazed that that amp with a matching cab didn't go for silly money as it's rare to see them together. Let us know what they're like