It brings ALOT of attention
I have split 10's a total of 3 times. One was at a burn joint that I was growing weary of, and I wanted to see exactly how clueless the pit really was. They were dealing a 4.5/6 game with crappy rules and I jumped from one hand at $3 to 3 hands at $100 (table max) in 3 moves. 2 of the three hands were 10,10. I split them both, got a 7, 8, and two 9's. Dealer had a 10 under his 6, then busted with a 10. This got the PC's attention, but I didn't get barred.
2nd time was at a major property in Vegas spreading 1-4 in green at SD. Split 10's and got booted 4 hands later, 35 minutes after walking into the place.
3rd time was at a place that has no fear of counters for good reason. Splitting tens there really got the PC's attention, but only because it screwed them up on the payout for a side bet that I was playing.
In short, I have found that splitting tens definately gets their attention. From cover purposes, you get about the same effect by splitting tens or by doubling your bet spread. Doubling the spread is a hell of a lot more profitable, though.