Without sounding like a smartass my suggestion would be try a box of each. My second suggestion would be to keep the brass get a set of dies and work up a load that satisfies you But thats just my opinion :!:
I've shot the 32gr Hornady Vmax, ~1" at 100yds so far, but I only have a dozen rounds down the tube, expect it to get better with more shooting. The 40gr Hornady loads, from what I've read don't shoot as well in other rifles with the same 1-12" twist. I've got a box of 40gr, haven't shot em yet, but will try em. I've bought 100rnds of factory stuff so if I decide to reload, I'm all set....unfired brass is not available yet, some once fired available on the net and at ebay, though.
I guess I'll answer my own question that started this thread. Had the NEF out Veterans Day with two boxes each of .32 gr and .40 gr. Hornady V-Max. POI is slightly higher with the .32 gr which what I expected from the lighter bullet. The .32 gr groups were also tighter but not by that much. Went out to 100 yards and did not have to adjust the scope after sighting in at 50 yards. Next time out with it I'll take it out to 200 yards and see how it compares with my .223 NEF and my 22-250 Ruger Mark II Varmint.