Handle the rods you can. As mentioned above, every manufacturer (and even lines within each manufacturer) will be different in power and action. For example, generally, St. Croix is known for having a slightly heavier and faster build than say, Fenwick. Fenwick, however, also produces the Aetos line which tends to run much faster than most lines from most manufacturers. Ultimately, it comes down to the type of feel YOU like while fishing Senkos. Should I assume you're also looking to fish other finesse soft plastics on it as well, I would suggest something on the faster side because you aren't going to have a lot of weight dragging the bottom, and being able to drive a hook set at distance is much much easier with the stiffer/faster rod.
What gets sacrificed? Maybe some casting distance and faster rods tend to be a bit more brittle at the tip and have narrower lure weight ratings. If you're responsible, and buy from a company that offers a strong warranty, this isn't a problem, but broken tips are the biggest complaint I've heard regarding X-Fast tips from fishermen in general, and it's 95% user error.
For that price range, Avid/Avid-X, LTB, and possibly used Legend Elites are available from St. Croix. If you ask enough people on here, you'll get answers ranging from Shimano to Powell, Dobyns, Daiwa, etc. Figure out how fast an action you like, and then go from there.