We receive a few requests from folks upgrading from the 7100. It really annoys us as we haven't received approval to order the 8100 from our admin security (we won't be upgrading to BES 4.1 for a while due to a lot of remote Exchange 5.5 servers). It doesn't leave a lot of options for our users who dislike the larger form factor.
BBs through my history: 957(8MB), 7280, 7290, 8700c
BB Now: 8820