Mounting it forward does not reduce your FOV when shooting two eyes open, which is the proper way to maximize use of a red dot sight. The biggest mistake most people do with RD's is that they treat it like a scope; it's not. With an unlimited eye relief rating on 1x RD sights, you're allowed to mount it pretty much anywhere you want where there is rail space, but by mounting it too close you end up getting a blind spot from the tube of the RD with both eyes open. Mounting it close may appear to increase FOV when shooting with just one eye because you've already limited yourself to shooting through only the RD tube rather than letting both your eyes process what's ahead and allow the red dot the 'float' over your targets.

Of course in the very end it will be dependent on one's personal preference, but I feel like many folks who go with RD sights should've actually went for 1-4x Scopes instead based on their shooting styles.