The wonderful thing about an 870, or HP9 is the more it gets used, the better it works.
I had an HP9 for a few years, and the more rounds I put through it, the smoother it ran. Went and grabbed an 870 Rem brand new and man... What a pain having to shoot it and shoot shoot and shooooot it to get it to where the action was on HP9.
I wouldn't worry about adding a choke to the 14" barrel, just buy longer barrels for it for hunting etc that are threaded. The 14 is all but useless for clays, but it's a lot of fun for CQB type stuff. You know, deadly pop cans, bottles etc..