I think all the colour (more white ext) eye colour (both blue ext) is all
a bit of bolax, I think you could certainly have not problems crossing
merle to merle, but that in some cases, you certainly could, so is it worth the risk ?
As you say, some breeds that are merle, are always crossed, with little problems
and also the hybridisation of lurchers, means a right mixed gene pool, even in 2 merle's
so this should lessen the risks, butstill, you would kick your self if you ended up
with a deaf litter, or with some of the other problems associated with this cross.
I myself wouldnt