I've had my Clearos for a very short time and they've already started the dreaded leak (only 1 of the 5 had the thicker tube - neato :/ ). With one of them I took an old KR8 carto tube and converted it to a metal-cased clearo (standard CE2?) - I like it, but It seeps just the tiniest bit since I didn't think to use any sealant (and figured the rubber seal would work ok?). It was a very snug fit, so I doubt it will come back apart without breaking something, but the seepage is so minor, I don't even worry about it - a lot less than the clearos by far at any rate, lol...
Oh, mine were the standard size clearos and the standard size KR8's I had were about 1mm longer than the clearo tubes, so it was the perfect size - but I don't think this would work with the XL clearos...