Winston.. I had a multi fuel previous to the C4 with screw thread inlet at the bottom and sliding air wash inlet on the top of the stove.
I also did wonder if just having 3 settings on a lever would be a issue, but to be honest I think it’s works fine.
The glass blacking up I suspect is because of its small size, once all fuel has been burnt it’s cooling down during the night and residue fuel leaving deposits on the glass.
It’s just case of a bit of spit and a wipe with newspaper to clear anyway.
I decided on the C4 for its single control, as Iam away from home a lot, so it’s left to the wife to run, she just wants fire and heat quick and easy.