You still can use 4x margin so even if it is not true, you can make 10k wall with 2.5k btc.
Nothing wrong with that -- could end with massive short squeeze.

Only those who were grandfathered in can do 4x. Some get 2.5x, new users get 2x. You'd have to be insane to full leverage at 4x in this market....
I had 4X available on only one of my accounts. This changed to 2.5x recently. Exactly how is the account max leverage decided now? Will it change unexpectedly again? Is there some official word on all these changes? Pre-announcement of all such changes (here + @bfx + optional e-mail) would be very good, especially when it comes to micro structure / engine patching and changes in the actual trading contract specification. These should be published several weeks in advance unless there is emergency requirements. Also, maybe you could push changes to some fixed weekly "maintenance window".
In the 4 months I've been with BFX there's been at least three major changes to their margin trading facilities, each time my first indication that something is up has been trades not closing or error reports piling up.
First they dropped the leverage, then they came for order entry flexibility (changed it to work more like a cash market) then they hit short duration traders with fee increases (this segment should already bring in significant fees, and contain most of the mm / statarb activity, which arguably provides quite a bit of value to BFX and its users. (any secret tobin supporters at the BFX offices ??

Due to my lousy scripting faculties/attention span I failed to notice something amiss until the losses had piled up. Turns out all my closing orders for the last 2 days were rejected due to unsufficient funds (opening was fine. go figure...). Before this I was attempting to exit by transacting -1.01 x current_position. The quick fix was to change this to 0.99X, microstep across zero and then opening up to full size.
While it was arguably on to me to fix proper reporting / cross-checking etc to start with, a simple e-mail detailing the execution logic changes would have gone a long way. I can only imagine how it would feel to someone with a more sizable account.
And to top it all off they then changed the swaps so short duration trades would cost a minimum of a full hour of interest. Changing interest calculation rate to 1/second (and/or) an option to disable auto-close of swaps would fix this.
The order entry issues could be improved on by using some liquidity-adjusted margining measure, as then you would need real money to effect real change.
Anyway, i heart BFX and trust them like i trust the stamp. I just want them to be even better (and plz give me my leverage back, i'm mostly hedged elsewhere anyway, free my bitcoins!)
EDIT: note to self, check which thread before posting next time. thought this was the bfx thread, oy well. good day to you all!