I had a 94 % upgrade sucess rate once I achieved the lowest tier (25,000) on Continental.
Of the three segments not upgraded two were a round LAX IAH LAX trip booked @ $ 186.50 direct through Continental.
On the other one I checked in after my boss, I had more current year miles, he is multi year Platinum I am first year since I switched from Delta (Who admits they discriminate by fare class) to Continental.
Anecdotal probably - However ???
------------------
"A Southwest line never gets longer, It only gets wider"