I tried it, and had issues getting my mix loaded into the tubes in an expeditious manner, but only tried a couple of times.  My most recent CLC kit came w/ the "extras" deal and had a roll of the Epoxy Filleting Bags that CLC sells separately, and they worked a treat.  There's more than enough on one roll to do a whole kit and they load pretty easily.

 If you are doing a big project or need speed, they sell the Six10 thickened epoxy in caulk tubes w/ static mixer nozzles.  Pricier on a unit basis, but it's an efficient way to lay down epoxy beads quickly.  I don't know if it's thick enough for fillets, though. I've used similar in industrial contexts where we had to get 'er done quickly and didn't have room for error.

   thanks for the tips!

I tried a MAS WoodZilla tube and, although it worked well, I either got only 2/3 of the tube contents before it came to a hard stop, or the tube was only 2/3 full. Also, the contents are a different color than what you get from their wood flour product sold by CLC. 

I tried sandwhich bags and that caused a mess. I tried piping bags we had on hand from my daughter's baking efforts. Too small. The most success came with a combination of the bags sold by CLC (extra big and easy to fill) and my 12-year old daughter's mad cake decorating skillz. With her at the helm of the piping bag and me guiding the tongue depresssor, we laid down some awesome fillets for the forward and aft seats on our Passagemaker Dinghy.

   I may be recruiting a helper!