That is nonsense. I could point out 5-10 venues that offer excellent spreads, low enough commission rates and stable liquidity for retail traders to get engaged in. When it comes to market depth that is an entirely different chapter. But your claim is not correct. In fact LMAX is a more expensive trading route than Interactive Brokers for retail traders. We can have an honest discussion comparing the two if you like as long as we stick to facts.
Not available here in the U.S. (and for the most part Australia, Canada, Singapore etc) so many of us have no interest either way.
Refering back to the original post: As far as I know LMAX is the only FX execution venue (available to retail clients) which publishes a central limit order book. Happy to be corrected though if I am wrong. Do IB offer this? It's also pretty essential if trading on the timescales described in the paper that your LP doesn't have the option of 'last look' rejection. If they do then you'd rarely get a fill unless price is likely to move against you. I know someone who's involved in coding MM algos (including FX) and he tells me they use models, not dissimilar to the one described, to predict very short term price movement. They then use these to determine whether to accept or reject an order. Sure, if you are trading FX on a longer timescale there are a myriad of choices available, but I'm not aware of any venue other than LMAX where the strategy would be viable for a retail client.