".....I like the field of view of the Swarovski, over 30' more, but the Leupold has 4.4" of eye relief compared to 3.1" on the Swarovski. I will be hunting plains game and buffalo with it....."

Well that's the trade off.... as one goes up, the other goes down.

For the 375, I'd say the 2-7 Leupold would be a fine choice (especially if you plan on using the 375 as your single, all-round, rifle). I've been told the VX-2 is the strongest variable available?, and for serious rifles, I much prefer the Leupold "long eye relief" configuration (vs. Zeiss, Swar, etc).

FYI, I went with the following:
458 Win Mag; 1-4 Matte Leupold VX-2
338 Win Mag; 2-7 Matte Leupold VX-2
300 Win Mag; 3-9 Matte Leupold VX-2
Spare/in rings; 2-7 Matte Leupold VX-2 (fine for all 3 cals... at 2x for the 458)

All rifles are (std length) pre-64 70's and I've fitted all so there is 100% scope interchangeability (all use Talley lever rings)