Optimum speed and altitude for R2

For the R2 sensor what would I expect in degraded performance if I was flying at 80m AGL and at 6m/s when compared to the optimum flight speed and altitude?

I came to ask a similar question - Looking for the optimal height/overlap/speed in various scenarios. Today I flew at 60m, 50% overlap and 11 mph in a wooded area and I’ll be processing soon. I do wonder what I could achieve on a more conceptual basis for contours, like in a county with no topo on a prospective land development site, could I fly say at 300 ft / very low overlap and fast to generate “good enough” topo? Would help to get a best practices FAQ or video on this. I have some construction sites that are wide open and I’d assume I can fly those faster / less overlap but don’t want to have to redo stuff.