Not a bad choice. It's silicone, so it's hypoallergenic and can be cleaned and sterilized. You could easily interchange it, just make sure it is sterile, especially going from you to her. The reviews say it gives a great prostate massage, and that's the stimulation you're looking for on you. Also from the look of it, the Pro Touch Plug would give good g-spot stimulation too - from the shape and angle. I think it would work for the purposes you're looking for.
I have this toy, and although I found it adequate for prostate massage, it didn't do much for g-spot massage on my partner. If I had it to do over again, I would probably get the G-Force instead. Although the ProTouch has a vibrator and is harness compatible, I like the looks of the handle on the G-Force. It has a little more girth to it, but it is still relatively small. It is longer and should allow for more manipulation to better contact the prostate and the g-spot.
I'd second the G-force for mixed P/G-spot play. The Pro-Touch was really better as a mild clitoral vibrator than a G-spot vibe.
The G-Force gives a good handle and a very controllable head for both P and G-spot stimulation, and it's much easier to keep it pointed in one direction. The downsides are that it doesn't vibrate and it is bigger.