I've had 3 of these over the last 3 years (since I started playing). And all of them have been good discs. But I settled on the Proton, as it's the most stable plastic and most useful for me. When I first started playing, the Insanity was one of the longest discs for me. But now that I can throw farther, smoother and with better technique, it's turned into my understable speed 9 FW disc.
I had 2 Neutrons and now this Proton, and all of them feel about the same and throw about the same. The first Neutron I had was a bit lighter, maybe 169g or something. And it quickly become too undestable for me as I started to learn how to throw better. Then I had a max weight Black Ink Discs Neutron and it was sweet for awhile as well. But it also became to understable for me. Now I'm on to a max weight Proton and it's perfect for me for now.
The feel of this disc is very nice to me. I love thin and medium depth discs and this thing is VERY thin for a FW. NO dome, 100% completely flat top, but somehow still has a nice rim to dig into. Has a fairly sharp leading edge on the rim, and the Proton plastic feels really good in your hand. It's that slick shiny hard plastic, but has grip still. Comes out of your hand very clean.
Flight path is like 9/5.5/-2/1 ish if thrown correctly. If not thrown well, it's like a 9/4/-3/1. It's a bit touchy, but not real bad. But I do have to be careful about the angle I put it on, or it can turn too much. I've never really thrown it so bad, that it turns into a roller, but if I throw it flat and hard, it can turn kind of quick and get to ground right fairly short of where I wanted it to go. But when I get it on a hyzer angle and place it a little out left, good lord, this thing goes a long way and has a nice flight path. It will flip to flat, then start it's steady slow leak out right, and it gets pretty far out there (about 20-40' right of center), but then it always has a soft finish back to the left. For a net throw of about 10-20' right of center. So it's really good for a hole that doglegs right, but where you have to make SURE it won't continue leaking out right (like a Maul might do). It gets out there to the right, but always comes back at the end on a forward pushing fade. It's a pretty unique flight path that I can't replicate with any other disc. I don't throw this thing a lot, but when I need that shot, it's SO nice to know I can just throw it and forget it. I don't have to manufacture an amazing shot, it just does it.
Also, at speed 9, it's kind of like a FW, but not quite like a driver. It goes about 10-20' father than my speed 7 FW's, but the thing I like about it, is that it's easy to get that distance. As long as I throw it high enough, it will glide and get good distance. Which also reminds me, it is also a bit touchy for distance with it's height thrown. You have to get it medium to medium high or it won't go that far. I think the glide is a 5, but only with the right height. Otherwise it's more like a 4. If I throw it more on a flat rope height, it doesn't get anymore distance than my speed 7 FW's.
It's also a great hyzer flip FH disc. Can throw it on a fairly steep hyzer angle on FH, and it will flip up to flat, get out left, then come back softly at the end. The flat top and thin overall depth make it feel amazing for FHs. Just have to be very careful about the angle or it will instantly turn over left and into the ground. But that also makes it one of my favorite recovery discs for longer rescue shots from the left side of the fairway. Because it's so understable, I can throw it out right from the left side of the FW and it WILL hold that angle the whole way.
Overall it's a great disc and one of the better distance discs for beginners or intermediates that need more easy distance. Along the lines of a Maul or River. But because it's a tad touchy, I'd always recommend the Maul or River first. I think the thin overall depth and lack of dome make this not quite an amazing disc, and just good.