If it works for a few months, then it's not enough time to tell. I had a 14" GG with my 22" Jar. All was well for a while then overnight the jardini nearly beat the GG to death. I've grown to accept the fact that I might have a 300 with nothing but a jardini, but I'm ok with that. They're beautiful and totally worth their own tank when they get big. Their presence is more powerful than a big stocked tank.
Right now I have my jar in with a 22+" marbled pim. Every once in a while the jardini will tear fins/scrape the hell out of the catfish, bit it recovers quickly. I'm still tempted to remove the cat, but he's too good at cleaning up.
Bottom line, there is no way to tell. I would ignore the experience of a jardini under 12" That's just a little guy! LOL. (and yes, they don't care if your hand is in the tank, they might bite you!)
Just to give an idea of their ability to individually demand visual dominance of a tank, here is a pic (I know you and a lot of others have seen it, but a picture is worth 1000 words).
Right now I have my jar in with a 22+" marbled pim. Every once in a while the jardini will tear fins/scrape the hell out of the catfish, bit it recovers quickly. I'm still tempted to remove the cat, but he's too good at cleaning up.
Bottom line, there is no way to tell. I would ignore the experience of a jardini under 12" That's just a little guy! LOL. (and yes, they don't care if your hand is in the tank, they might bite you!)
Just to give an idea of their ability to individually demand visual dominance of a tank, here is a pic (I know you and a lot of others have seen it, but a picture is worth 1000 words).