All rootstocks have some negatives. The only real negative to B.490 that I've found is potential for late winter injury. Penn State's website still says nice things about it...supposedly based off their 2015 Production Guide. If the guy you talked to had specific knocks against B.490, I'd like to know what those were.
To be commercially successful, it had to win production space from B.118, P.18, and the well established MM.106 and MM.111. No shame in not winning that battle. The fact that it can be propagated by hardwood cuttings is enough for me to play play with it. I am also going to try rooting cuttings of the Novole rootstock which never caught on for good reason. While voles don't like the taste, Novovle gives a full size tree, slow to fruit, and and relatively low productivity. Still, I'll try it if I can get cuttings to root and probably use a smaller Geneva, probably G.11 as an interstem.