The United Clubs do not offer food for purchase. The Admirals Clubs I visit are also refurbished and more nicely appointed.
Also, Star Alliance does not allow access to First Class clubs for top tier elites on international itineraries, unlike One World.
As other have mentioned, unless flying Y/B fares your upgrade percentage is going to plummet. If you really care about upgrades and clubs, I would suck it up and continue to connect.