They're retail ECNs, not the institutional ECNs (Currenex, HotspotFXi, LavaFX, FXall, Baxter etc). IB offers 1/4 lot size, but it carefully does not classify IdealPro as an FX ECN, simply that it follows an ECN model. Still a fairer game than the spread-commission chop shops.
There are retail brokers offering Currenex and mini lots, but not all Currenex platforms are the same due to its hub nature.