I have had quite a bit of experience with them. I owned an old CJ7 that had a none functional Gas Gauge. Had to go on Drive Time to determine when to fill up. This did not work out too well.
So as you can imagine I had quite a few chances to use the Blitz that I had in a confer mount on my spare tire.
Well, all I can say is they leak. Not a lot, but mostly just smell and have runs of liquid down the side that gather tons of dirt.
To get the lid on tight enough so that it does not leak too bad you have to use a lever arm, like a screwdriver. This also means that the lever arm is needed to remove the lid.
If you can find them there are rubber bung style nozzles that you insert into the opening and flip a lever that expands the rubber seal. Just like a boat plug. These are by far the best nozzles. The screw in nozzles have the same problems as the lid, but have no place to use a lever arm.