I put that grommet in an SP tank on Friday, it was tricky but went in without any failures. I used some soapy water to lubricate the 5/16" O.D. fuel line and it was tight, but I am confident it will be a leak proof solution.
I have some of the kits that Steve notes above, but I am not comfortable pulling the barb fittings out and putting the alternate in place. I am sure the negative reviews are because the sealer is hardened in the tube, something he used to note in his listings but evidently has chosen to omit.
Mark