Running 50A of 220v is a bit of a pain - it requires 4 conductor 6 gauge wire, which is a pain to deal with, especially when you're doing runs in conduit.
The key point here is that 30A/220v service still requires 4 wires, 3 conductors and a ground. You can drop down to 10/3 instead of 6/3, though. and it requires a dual pole breaker, though its 30A instead of 50A. It's definitely less expensive and much easier to pull wire if the run is long or has bends.
There is absolutely nothing wrong with doing it that way. I use a similar set-up at home myself. It gives plenty of power, including enough to run two a/c units simultaneously.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL