The only time I find a wider FoV useful is in counting flocks of fast moving birds, but that's possibly because the vast majority of my birding is done in a wide open landscape so it tends to be focusing in on something you can see with the naked eye (even better FoV ;-)). I can imagine if you're birding typically tends to be close range in dense cover a wider FoV is a big advantage, but for me it's a nice to have rather than something I would ever stick near the top of my priority list. To be honest providing there's a decently large sweet spot, sharp edges are a luxury rather than need. Rolling ball doesn't worry me but obvious CA really annoys me. Balance is much more important than weight too, and with large hands nothing too small/fiddly. It's a good job there's plenty of choice out there for differing priorities and budgets.
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