2 hp vs 4 hp is pretty enormous in terms of surviving CC - it saves you from eagle eye, RoF, all bolts (when under 10 quanta), and thunderstorm. As an added bonus, 3 attack hits the adren sweet spot (though that isn't a huge deal in foldafolda's rainbow which uses heal instead (though if it's a buff-based bow, I don't know why it doesn't use adren)). About the only time I'd use the unupped over the upped in an otherwise-upped deck is in FG prediction situations where you know CC isn't gonna be an issue. I'd use the upped version almost 100% of the time in snovabows for arena.