Some good reading on the subject from previous LRH threads!
site: longrangehunting.com FFP vs SFP - Google Search
I am not an ELR guy but feel comfortable in shooting big game sized animals from 600-1000 yards, which is what I consider LR. I shot SFP MOA most of my life but have recently switched to FFP MIL and can't see myself switching back. I have yet to use a modern FFP reticle that has an issue with being too thick or too thin for big game hunting. The reticle IS thinner and thus harder to see at low power mags but low power is only used at close range shots where it is a "point and shoot" scenario. At longer ranges the magnification is up and the reticles are just fine.
Also it is a bit of a misnomer that the reticle becomes too thick as you turn up the power mag. With FFP scopes the reticle stays the same thickness in relation to the target as the magnification is increased so it is really impossible to have it be worse or unacceptable at the higher magnifications. If it is okay at 5x or 10x it will be exactly the same at 20x. I think some guys like to see more of the target as the distance increases but that is really just a mental preference IMO.
Much of your choice will depend on your style of shooting. If you don't use the reticle for anything but aiming at the center cross hair then you may not find as much to like about FFP. But if you use the reticle for holdover, windage, or calling shots, misses etc. then there is a huge upside to never having to worry about change in subtention due to a change in power.
One area that I now consistently use FFP is for calling shots, hits or misses, for my shooting buddies. With today's high quality optics a guy hardly needs a spotting scope to call all the shots in the field and with a nice FFP scope with a simple hash reticle a spotter can call shots and the shooter can immediately make any necessary changes. A very nice feature.
Also my style of hunting entails using mostly the reticle for holds out to 600 yards or so as this is approximately the distance where I don't have to worry about atmospheric conditions changing my POI. It is at these closer distances, 0-600 yards, that I may need to get off a quick shot and a mil hash reticle in FFP is about as fast as anything out there IMO. Beyond 600 yards I typically dial in based off my ballistic program and use the center crosshair as my aim point. But even when dialing and using the center it is still very nice to be able to read how far off of POA I was by using the reticle.
Whatever you do make sure you get matching turrets and reticle. It just makes for a much more user friendly and easier setup.