It's not just the tensioner.
I run a 21 tooth sprocket to get the low gear range I want, sub 10".
Without a slight mod to the tensioner then the upper jockey wheel will touch the sprocket and there's no "b" screw on it to stop this.
I run my lower chaintube alongside the power pulley and not under it.
I've found if it's under the pulley then it's the lowest point and it's possible to catch it on the ground when going over real rough off road tracks
This makes the chain run reach the tensioner at a constant slight angle.
This is just enough to wear the lower jockey wheel out over +10k miles.
And it's always the lower wheel that goes first.
Plus ~£5 every couple of years isn't going to break the bank ........