Debonair is like £42 and if you do a general service of the fork (non including the charger unless it really needs it) at the same time I’d think you’d notice a worthwhile difference. It’s quite an easy home job and the only vaguely specialised tools you need are circlip pliers.
Once you’ve converted to coil there’s no going back to air I don’t think as the spring can scratch the inside so it won’t hold air again.
The debonair should mean you can run a higher overall pressure (with less tokens) but give you a supple initial stroke. That higher pressure will firm up the mid stroke without making it spike as much as hitting the rapid compression in air you get from tokens.
There is also the luftkappe option too – which will give you an even bigger negative spring volume than the debonair shaft – although it’s a bit more diy fitting.