Hey Mike. I honestly don't know if there's anything to help you in this, but take a look at
Click here. This is a review I did about 10 months ago. It doesn't mention F5 at all, but it does focus on WAN Acceleration - CIFS/SMB acceleration to be exact - and problems we had in our testing. There are some "heads up" items in there for WAN SMB connections, maybe not useful at all, but you did say "any suggestion is welcome" :-)
This article will be of more use if you're also suffering long delays without the tunnel, and we did not get to test F5 products with it - the timing of the article was off for F5 to participate. Now F5 offers WANJet in this space, but I never looked at it as a reviewer, the stars just didn't align.
Don.
Nimbostratus