I've just been doing a bit more digging for comparison images and resolution obtainable with an 80mm scope and came across a few Peter K has on his K3CCDTools website of sunspots taken with an 80mm refractor at various focal lengths. A couple of the closeup ones are taken at f/14+ so it is possible to compare them with this
one which covers a similar field of view and includes the IIS
The K3 details are
here. Nice shots too.