Personally I would favor RSBFS for what you have for sale. RSBFS primarily touts only bikes listed directly with them. They are no longer dominated by listing bikes listed elsewhere. I sold a Ducati 900SL on RSFBS earlier this year for a friend. Were it my bike I might have sold it on BaT, but since it was someone else's bike and I had limited knowledge and history with the bike, I did not want to deal with all the questions which might get raised on BaT. BaT is to be avoided if you don't want to or can't answer a lot of questions about a bike.
The auction formats of BaT and Iconic are advantageous for bikes with significant market demand as auctions only work when there are enough interested buyers to bid up the price. The demand for an RC51, 9X6 Ducati, RZ500 or similar bikes everyone wants is high. The demand for esoteric bikes like the ones you are looking to list is narrower, so there is a greater risk of not achieving a good price. Of course, if you're willing to accept whatever the bid price is, BaT, Iconic and even Ebay will deliver this price.
GLWTS.
The auction formats of BaT and Iconic are advantageous for bikes with significant market demand as auctions only work when there are enough interested buyers to bid up the price. The demand for an RC51, 9X6 Ducati, RZ500 or similar bikes everyone wants is high. The demand for esoteric bikes like the ones you are looking to list is narrower, so there is a greater risk of not achieving a good price. Of course, if you're willing to accept whatever the bid price is, BaT, Iconic and even Ebay will deliver this price.
GLWTS.