I have mostly been trading FX spots using IB's IdealPro and occasionally do some FX futures options to express a sideway view. I see FX futures options are listed in CME/Globex and Dollar Index options in ICE. I wonder how are those listed-options compared to retail-OTC quotes by the likes of CMC/Saxo in terms of liquidity and implied vol ? I think there is no inter-dealer market among the retail shops (unlike banks), so they all balance the books via listed markets, and so their quotes should constantly be marked up? If so, why would anyone trade with a retail shop rather than using CME futures options given the decent liquidity and weekly expirations? That is, why would a trader go trade with a retail broker while the wholesale futures options market is available?
Liquidity is lower as demonstrated by the bid/ask spread. Commissions, fees and mostly margin requirements are also higher. And it's also more complicated.