Thanks for the welcome!
I was searching the web a couple of months ago, for GSO dob reviews and found this community - plenty of useful articles if you own that scope (or dobsonians in general). Yesterday I was again on the hunt for this Barlow + eyepiece + filter question and I ended up here again. I read the existing articles and found my question wasn't addressed yet so I decided to register and give it a shot.
I have ordered a Orion XT-8 dob (previously I've owned a cheap 70mm refractor...) - I also ordered a Shorty-Plus Barlow and a filter pack (both from Orion*) which has the Moon variable polarizer. I read that (and I'll quote):
"With a variable moon filter on a 10 mm SWA Speers Waler eyepiece, the eyepiece doesn't fully bottom in the barlow. But, the 2 mm gap seems to cause no problems."
Common sense tells me this statement is true - have you got any similar experiences? I can't wait to test this myself...
*- No, I ain't an Orion bigot - I just get their material because they have an official retailer here with fair prices and excellent service. 