I agree the splits dosen't really mean nothing it just looks good if you can do it, its like being an acrobatic martial artist dosn't make you a better martial artist. Have you tried Tom Kurz theaory? if not it could help you
personaly i would say that it is quite a good idea to train in both, beacause karate will teach you to puch, kick and block while ju jitsu will teach you how to grapple on the floor along with locks and throws