Anybody that takes blackjack seriously should own sim software. You plug in your game info and run a sim both with and without splitting tens, see what it costs, then determine if it's worth it to you. I personally never split tens because to me the added heat wasn't worth the added ev. Sim software also definitively answers the never-ending age old question, "Should I move to a more complicated count system?" To very loosely paraphrase Stanford Wong from a different but related matter, "Being able to add some extra chips to your bet more than makes up for it."