Thank you.
I have bought the foam UNIFILTER, but after little late thinking realised that it may not be the best choice for long distance adventure riding I'm planning - trying to clean it properly in the middle of Botswana or Mozambique - and carry all the necessary crap for it - doesn't appeal. I know that DNA/KN filters are frowned upon by offroad crowd because they may not filter as much as foam (but then paper filter - dry and in good order - should filter more than foam, just cannot be cleaned - that's why it flows less air in my understanding). But I have KN/DNA in my 1150GSA and Tenere (stage 3 where the whole side of the airbox is open) and so far after over 140 000 km all over Africa on those two bikes I didn't run into problem.
I should also say that I ride mostly solo or with one or two mates at most and I"m usually up front. So I do not ride eating dust for 100s of kms as some people who ride in group or race do.
I have read tons on the internet about this dust issue and while there doesn't seem to be general consensus on the solution (for some people grease on the lip works, for others not entirely), my feeling is that the problem isn't the filter, but the proper insulation around the lip of the airbox. I will try either the grease route, or - probably more robust - silicone, and see what happens.