Hello, I have a PF9 and like it very much. I have shot hundreds of rounds through it and no problems. Kel Tec had problems with the first run of them but have corrected several issues with them. The easy way to tell if the one you are looking at is a current version, is if it has a metal mag release. If it does, it is the current version and has all the corrected mods. to it. I purchased it for summer use, due to its light weight and thin frame. I think it carries well and almost forget I have it with me, which I think is the point of a carry weapon, not to mention it disappears when even light clothing is worn(T-shirt and shorts).
Is it as tough as a glock( and I have 2 of them) as far as torture testing, I don't know as I have never tossed the kel tec into sand, mud, water,etc. and tried firing it. I do know that mine has been very reliable under normal firing conditions and has functioned above what i expected from a weapon in its price range. I trust it as much as any of my other weapons including 1911 45ACP's, which have a history of stove piping spent rounds.
All and all, if you asked 10 diferent doctors about a certain thing, you would get 10 different opinions, which holds true to most things in life.
If you are happy with your XD, by all means stick with it. If you are looking for options to carry, them the PF 9 is a good option or as a BUG, at least in my experiences.
Just keep in mind that every maker will and has turned out a lemon or two in production. The PF 9 is covered for life by the company, so if you do have a problem, they will take care of it.
Just my 2 cents worth as a Kel Tec owner.