i pit for a guy that owns a Losi fuel gun and they work awesome. i can pull a faster pit stop with the gun and by myself than with a bottle or another person. the only thing i have seen with the Losi gun is that if the o-rings in the trigger get dirty the trigger tends to stick open. a little fuel on them cleans them up and makes the trigger move easily. yes with the Losi 8t there is no body trimming needed just hit the hole.
the guy i pit for really likes the gun because after a weekend of racing he can take his car home and there is not fuel all over the place. when its done filling its done no spilling no foming and its full.
on if it will do more than one tank and car, the losi holds 200cc of fuel, the numbers on the side of the gun start at 0 at the top and count down, so if u fill it to the top and fill a car u can see how much you put in the tank, ie 7 mins in a buggy and u fill 100cc there was 25cc left in the tank so you can send your driver for 7mins and be comfortable that he will not run out of fuel.
Losi fuel gun two thumbs way up