The Tick is dangerous to use all by itself. Look at today for example. A 15 minute chart of the DOW shows a classic bottom formation, then we got 2 nice up bars, and bam, the Tick is over 1,000. Then it stays over 1,000 for nearly the next 250 points up! Even trading off of a 5 minute chart, you didn't have much of a chance to sell short and exit for a profit.
I would combine it with other indicators (RSI, MACD, etc) to confirm an overbought reading.
If you're long, it would be a good sell indicator. Especially if it got to 1250 or higher. I hardly ever look at the Tiki. The Tick gives you a much broader feel.