I had a 917, and went to the TS2 this year. I had no plan to, but the difference was enough to convince me. Best thing to do would be to find a fitter, try both and see which works best for you. Who knows, you may even find that a TS3 works best for your swing.

The only problem with the 917 is it is only available as store inventory. Titleist is no longer shipping custom fit 917s. If I bought the discounted off the rack 917 and the shaft was not optimal, a replacement shaft + the 917 discount would still be greater than a full price TS wood. In the past near the end of the 2 year cycle, the woods have been discounted but still available for custom order. So a TS wood mid-to-late summer next year would be better down the road than an off the rack 917 today.

Skip the 917 and get fit for a TS2, you won't regret it.

917's didn't seem to do well in the UK. Part exchange values for 917 are already very low so here, it doesn't make economic sense to go for that option.
JT

Ts2 you’ll not look back!!
Best driver in years from Titleist!!

I actually love the 915 D2 over both the 917 and TS (so far)! I have the TS2 but I am having difficulty getting accustom to the feel/look. I have it configured to the same setting as my 915 (even put the same shaft in it and added 2oz of hot melt to make up the weight difference due to the 1/2 in shorter shaft) ... however, it looks closed at setup and thus I'm struggling with producing the solid ball flight that I produce with the 915 D2.

I agree with the comments. I recently upgraded from the 917 D2 to a TS D2. As much as I liked the 917, the TS is a far superior product.

I had the 917 and went to the TS driver, its much better all around, well worth the money.

A custom fit TS2 is the move to make if you can. It's worth it.

Ive had them all from the 910 on... In my opinion the Ts series is better than both the 915/917, and i loved my 917d3