I havn't seen anyone build a micro coil with ribbon wire yet. And I havn't tried the ribbon wires yet. Next time I place an order with COV I might pick a couple up to experiment with.
If you are still using silica, ribbon is the best, however with cotton, ribbon is not as stable as low gauge wire for microcoils. There is the tinman coil which is a micro with ribbon but looks ugly and does not give any benefit.