Stripping paint on stairs well enough to stain?

I'm thinking of doing away with the stairs carpet, and would like to paint it all with gloss, except for the treads which would have a dark stain. Pulling the carpet to one side I can see that the stairs have been painted with a grey paint (the upstairs floors are all the same). What is this stuff? Will the wood even be of a good enough quality to leave exposed and paint in this way? The house is 18 years old (Redrow).

What are my chances of being able to remove the grey paint enough (i.e. completely!) to get good results with a wood stain? I've only attempted stripping once, many years ago with a heat gun, and the results weren't great.

Even if I was able to stain the treads I have my concerns about people going flying while in their socks! If I can't stain the stairs then the backup plan is to white gloss the lot and fit a runner.

I would be inclined to recommend a runner.

If the wood has had grey waterbased paint applied, then a heat gun won't help.

You should be able to sand it back though. It ain't a 5 minute job though and you may want to use a MS Polymer "caulk" to seal the dynamic cracks where the treads meet the risers.