<edit - everyone else beat me...> Despite the fact that a couple of production planes might outrun the 10 by a bit, there is that pesky price issue, and on that the -10 wins hands-down... <end edit>
Of course, there is the Lancair ES - the kit-cousin to the Cessna 300. Again, you will spend quite a bit more money for those precious extra knots.
One to watch that might give the -10 a run for the money from a value perspective is the
Ravin 500 (a kit from South Africa modeled after the original Comanche). Kit cost is only a tad more than the -10; speed is advertised as considerably faster; and useful load is an incredible 1700 lbs. Stall speed is a bit higher, but the stubby gear do look up to the task of landing on short/grass runways.
Adept Airmotive is currently assembling one to test their 320hp turbonormalized engine on, which would make it even faster while saving 100-200 lbs over an IO-540 (of course, their engine might do the same for the -10, but might also propel you right past Vne). The Ravin has plenty of Vne "headroom" compared to the -10 (according to an old email I have from them), so more hp and/or turbos need not cause you to "throttle back."
Even more interesting is that Ravin is currently working on duplicating Piper's evolution of the Comanche to a twin engine version. How about a pair of IO-390's anyone? Or, a pair of
DeltaHawk 200hp Diesels for a 2,000 mile range? Oh, my poor bladder - but with 400hp for climb and the ability to throttle back to 5gph/engine, with such an airplane you could easily cross either pond.
By the way, you COULD build a Ravin with a single DeltaHawk. Apparently they ARE delivering engines now.
So, there are some options.
BUT (and I fly a plastic airplane) - there is no other community so helpful as the RV community. Just as with individual aircraft components, support is a KEY component of any product. Factor that in accordingly!