Heh, at work that's actually how we've load tested swing arm brackets in the past before putting the TV on it (back when they weighed a helluva lot more). Most of the mounts we use are pretty cheap (generic chinese ones ), but make sure you know what you're actually getting. Some are rock solid and way more durable than you'd expect, while others are incredibly flimsy or hard to get the TV positioned and stay level, regardless of price. That's the big thing you'll run into with the crappy ones (again, no real bearing on price), is they'll sag when extended, or be difficult to adjust to how you want it.
24" stud spacing does make things pretty tight though, you'll pretty much have to have the mount centered over a stud bay, and depending on the bracket probably have to put the lag bolts in at an angle. If it's not already where you want the TV centered, you'll need to make sure you have enough movement on the bracket to compensate.