Well, the case for a server being 1.24 only will most likely be a test, a hotel or a server full of annoying Polish kids. Or both (a test server with annoying people is what I mean is possible, but sometimes it's alright). If you don't mind the loss of those, you'll do fine. But I gotta admit I do like to play tests every now and then. You should be able to play on most servers I think (I don't know exactly, I hardly play with 1.23 so I'm somewhat assuming the case here, but sometimes I do check the serverlist with 1.23 so I'm not completely making it up).