Yoshimura is now making slip-on exhaust cannisters for the EX250F.
The Yoshis are a bit lighter than stock. The centerstand is retained; there is a bumpstop for the rubber mount on the centerstand to hit on the left canister; a nice, flat tab was welded in the perfect place for it.
Installation is quite easy. Unbolt the stock mufflers, pull them off, slide the mufflers on the pipes, and put the clamps around the canisters. Then loosely bolt everything together, adjust them to your liking, and bolt everything down. The instructions are pretty good, though you may not need them. They even tell you how to clean the canisters properly.
Make sure to note that Yoshimura sells several different styles of cans. Make sure you know which one you're getting before you order. Contact your retailer or Yoshimura directly to find out which style is available.