Keep in mind that it's possible to earn status on *A partner programs for far less than the 50,000 miles UA requires. For instance, OZ allows you to earn Diamond status (equivalent to *A Gold) by simply flying 40,000 miles every 24 months. A3 allows you to acquire it's *A Gold status by collecting 48,000 tier points in year 1 then collecting 24,000 in subsequent years (A3 used to be super easy to get Gold status if I recall correctly it was collecting 24,000 tier points gave you 3 years status on A3). One major benefit of having status with a foreign *A airline is you can waltz into a United club anytime you want so long as you are flying a *A airline (even if it's strictly a UA domestic itinerary). That would save you money off a UA club membership. Milage accrual may also be better since it's based on distance flown and not money spent. You also get all of the other benefits tied to *A Gold, namely priority everything.
The downsides of holding foreign *A status would be not having access to UA specific benefits like CPUs, GPUs and RPUs along with complimentary Economy+ seating.
Would be interesting hearing from fellow FTers which *A program is best if you don't fly a lot on *A but want the perks of *A Gold.
Safe Travels,
James