Another consideration for slide work is the shape of the fretboard, i.e. is it flat or radiused (rounded a little)? Almost all steel string guitars have a radiused fretboard these days, and nylon string guitars have a flat one. When I started trying to learn some slide guitar a few years ago I found I needed a flat fretboard with steel strings (I can't believe you can get any type of sound from nylon strings with a slide--but that's just my prejudice). So I am still waiting for the right guitar before I get serious about learning slide. There are, no doubt, some styles of slide guitar where a radiused fretboard would be acceptable.

My advice is to put sound somewhat ahead of feel. You'll get used to the feel of the guitar you use and then everything else will feel slightly wrong anyway--until you get used to that one too.