That tensioner looks nice! Maybe you could make one like it that uses a spring instead of the long arm. Although I'm sure works great just as it is.
Yeah, I tried the spring set up, with this and it didn't work well at all, I figured out later how I can make it work by adding a stop to the arm that is spring tensioned so that when starting engine it doesn't over extend and throw a large amount of slack in the chain causing it to come off.
If a bike has a pull start and the spring tensioner is setup right that would be OK, but I find that the rigid Idler/tensioner set up is the most trouble free if a person is gonna run an adjustable idler/tensioner at all, I have never had a chain come off of one of my bikes accept when I had the spring loaded tensioner and I have a combined milage of around 2,700+ miles on them, I live in the country and ride mainly on rough old dirt roads and I have zero chain issues with how I have mine set up, my other two bikes just have the basic kit bracket with one of the HD Rollers I made made up and put on them, they have no extra bracing at all and one of them doesn't even have a screw through it because the bike frame where it mounts is oval instead of round so there isn't any way it can rotate on the frame as long as the bolts are tight.
There are several thing that have to be considered when using the kit parts, many times it all depends on the bike it is being used on, which will determine what mods may need to be done. each bike has it's differences and in my experience that will dictate what one needs to do to make it work out to be fairly trouble free/reliable.
Everything one needs to know can be found on this forum, and that is what makes this community so valuable for us all in my opinion, a whole bunch of really smart, creative and just overall great people hang out here.......