low premier upgrade chance for Premier Gold?
As a Medallion Gold, I have been upgraded every time I booked an economy fare with Delta. All of them are short one hour flights, so I can't speak for the chance of upgrade for longer transcontinental flights. But based on the fact that I have up graded every single time, I would guess that, other than the major routes like LAX-JFK/LAX-ATL, I would have pretty good chance for upgrade.
On the other hand, I am doing a status match challenge with United (Premier Gold), and I have flown a few LAX-SFO routes on United a few times, and I have yet to clear for Premier upgrade even once. (Though I did get upgraded once for a SNA-SFO flight). The only perk from United is the access to Economy Plus at booking, which Delta took away from Gold status earlier this year.
I am not sure if this is coincidence, but is it true that United generally has pretty low complimentary upgrade among the major airlines?