I don't think there is anything drastically different. The main effect of high base resistance is that you have to run the device at lower currents so the Ib*Rb drop is negligible. otherwise this IR drop will add curvature to the design which may not be modeled accurately. It also adds a non-ptat error that cannot be easily trimmed out.

I don't know why smaller geometries would necessarily make the base "wide." Quite the opposite in fact.