There is no simple answer, but if we were to ignore any potential building code / soils / environmental issues for the moment, I would say it should be technically feasible. I am not specifically familiar with Alan's installation but according to the website:
'How are they anchored?
We anchor metal garages for free to the ground or asphalt with 32” long rebar. We anchor it to a concrete slab with wedge anchors. Another optional upgrade is mobile home anchors if the garage is going to be placed on the ground.'
Now I don't know if 32" long rebar anchors are suitable for all their structures, but if they are, then with a bit of planning you should be able to obtain just as good (actually better) anchor to a wood joist system. Now will that hold up to storms, clay soils, etc; that is where it gets more interesting. How will you support and anchor the floor? Would you place the joist system on anchored piers?
Have you called the company? Ask them what they would suggest. I will warn you, if they are like other companies I have worked with, you may not get an intelligent answer the first time. Don't be afraid to call more than once. Also be aware that they may well outsource installation and as such you would be better talking to the LOCAL installer.
