I like my Mark 4, but the fact that the M3 turrets (MOA) don't match the reticle (mil) really bothers me. I also don't like that its not FFP. I'm thinking about selling it and getting the vortex PST 2.5x10x32 FFP. I know the vortex is considered slightly lower quality glass, but on practical terms the Vortex seems like it has better features.

The only thing I don't like about the PST is the small objective (32mm) might not be good in low light hunting scenarios. I use the gun (SPR type AR) for Coyote hunting. I also don't really like the shim type zero stop compared to the true zero stop on the mark 4.

Anyone who has both scopes have any opinions?

Sell the MK4 and buy a Burris XTR2.

Or this:

http://www.natchezss.com/2-10x36-tactical-precision-scope.html

That particular PST has an excellent optical design and corresponding glass. I was very surprised by how good mine was.

Damn, The XTR II looks a bit nicer than the PST.

ETA but No Illumination in 2.5-10x

Yes

I had a MK IV M3 and I now have the Vortex that you are talking about, I have read  that the glass in the PST line is very close and in some cases better then the MK IVs. I had a 6-24 PST and it was real close to a friends 6.5-20 ( I think that's what it is) MK IV. My 2.5-10x32 is real close to what my M3 was but it's a no brainer for the matched turrets/ reticles and illumination. If Vortex would offer a Razor in the 2.5-10X32......I'd be in for two.

I'd say sell it and get the Vortex but I done that long ago, I no longer own any Leupolds. Mostly I have  PSTs and a Razor, saving up for another Razor.

I have a Nikon Tactical from around 2006 in 2.5-10 mildot. I bought a PST 2.5-10x32 to replace it, and it was in no way better than my Nikon. Side by side, the light gathering, clarity, edge distortion was equal. The only thing the PST had was illumination, which for me is not important. I sold the PST and kept the Nikon.

If you were looking to go to something in another class (S&B, or NF -15x or such), I could see the swap, but to stay in the same power range, there is little that the PST offers beyond a lower mounting height. I don't care about the mil/MOA difference. I've used that platform for years and it's automatic calculation for me.

That Nikon tactical (I think they called it the Monarch-X) was a very very good scope. As dated as they are, they are still going for $800 or so today. Optically it may be equal to the vortex, however I disagree that the only advantage of the PST is the illumination. The biggest factor is the matched mil/mil turrets (the exact reason the OP wants a different scope) and the reticle. The PST is also FFP, although for this magnification range it's not such a big deal.

I own 3 Viper PST scopes... definitely worth it.