If your only going to bowl on a THS, then your HP3 balls are most likely all you will need, unless you are speed dominate/rev challenged, then a asymmetric ball from the HP4 line may work well for you. 
If you are going to be bowling tournaments were you may encounter heavy oil then the HP4 balls would be a good option to consider. 
However, the HP3 Idol (symmetric) would work very well on medium to heavy oil as well.

Blend the lines for what you need. Good to have a variety sometimes.

You could stay in the HP3 line and jump up from the Dare Devil to the Idol. That's what I would do.

+1 on Idol.  That ball is special.

You can't go wrong with the Idol and Halo. I threw my friend's balls over the weekend and they are definitely worth owning. The Halo was like combining my Rip'd Solid and Hybrid into one ball. Similar length to the Rip'd, but stronger off the spot like the solid. I reached a point where I got left enough where my solid would roll out if sent it out, but hook too much in. The hybrid wouldn't quite turn the corner enough to kick out the corners. But the Halo did exactly what was needed. In fact, I had to move a few more boards left.

The Idol is similar but smoother. I have owned/tried a handful of balls with the nano cover and none have disappointed.