My issue with your plans (that sounds rather dysfunctional, doesn't it!

) is that you are selling your only pair of speakers. I believe Murphy orders and builds to order so he is not carrying several $1,000's in inventory. It might take a couple of weeks to get the BMR's (I am totally guessing at two weeks, and could be longer if he has other obligations).
That is a long time to go without any speakers.
If your card can carry an extra $1500, you can order the LS50's from Amazon. Their returns are very easy and they are quick to credit the refund back to you once they get the speakers back (none of this 6 weeks BS). Ideally you will still have them in house when the BMR's arrive and you could compare them with the KEFs to know for certain which you like better.
If $1500 is pushing things, perhaps the Uni-Fi at $500 will work? They are supposed to be shipping in 3 days! It would be interesting to know how many pre-orders Amazon has for these.