I'd like to know more about clipons
What are clipons?
Clip-ons are kind of like two-piece handlebars that "clip" onto the upper portions of each fork leg. Though the 250R has two-piece bars, they are not true clip-ons, since they attach to the top triple clamp and are fairly high. To see the difference, look at a stock bike (left), then check out a modified bike (right).
Clip-ons usually result in a more forward and lower riding position, great for moving weight forward and getting good front end "feel" while racing. Usually the more radical sportbikes will have them mounted to the fork tubes directly below the top triple clamp. The drawback to using them is that they can be uncomfortable over longer periods of time, and you will most certainly have clearance issues with either the fairing or tank, especially during low-speed maneuvers. Hence, The Disclaimer: Consider that Woodcraft makes their "lowered risers" and also makes "clip-ons". If there is no difference, why would they invest the money to produce both options?
Note that the Woodcraft lowered risers (left) sit up a little higher than their regular clip-ons (center) to give you more clearance. Woodcraft vs stock bars/risers at right (stock is on bottom of photo).
Yes, Woodcraft (and many companies) make clipons that will fit a Ninja 250's fork legs. BUT... The reason Woodcraft makes lowered risers is because regular clipons don't work well on the Ninja 250. Yes, if you're running a streetfighter you won't have clearance issues with the fairing, but the tank is a different story.
How do clipons improve handling?
First, the riding position is more conducive to countersteering and gives a sense of added control (unless you lower the suspension too much to get them on). The grips and controls are lower and more forward, putting more weight over the front wheel.
Second, lowering the chassis to enable installation lowers the the center of gravity slightly, and also reduces the rake, trail, and wheelbase a bit. The stock ex250 has a higher rake angle than many sportbikes, and so it is easier to ride, though not as quick in turning as it could be; it is quick to steer because it is so light. So, by reducing the rake and trail by raising the fork tubes a few centimeters, you can find a spot in the steering geometry which is both quicker steering and still quite stable.
Installing actual clipons (not lowered risers) involves a bit of trial-and-error and willingness to experiment. You have to realize that you will need to have some fabrication ability and patience to put real clipons on your EX250. This is not something that many people have done, so you'll probably be on your own. The Board's general recommendation is to use the Woodcraft lowered risers if you want a lower riding position.
Which clipon models will fit the EX250?
Many of the major companies have quit making clipons for 36 mm forks. Regular clipons have clearance issues (see above). If you really want them you can search for 36mm clipons. Any of those will fit the forks, at least.
These are the known choices:
You could get a machinist to custom build a pair; basically just a 36mm clamp, with a 7/8" bar bolted/welded to it.