I've got a reservation to SFO in two weeks, and just today, received an email offering a buy-up to F. My friend (GM) is already in F, thanks to my CR1s. In the email, I was offered $430, but also given the chance to use miles. However, .sux said that I'd have to pay a $75 co-pay, per segment.
Rules for Premier member co-pay exemption
Premier members will not be a charged a co-pay on routes within the US-49 and Canada and from the US-49 and Canada to Hawaii (except between HNL and DEN/EWR/IAD/IAH), Mexico, Central America, the Caribbean or Northern South America (except between EWR and LIM). Premier members will also not be charged a co-pay for flights within Intra-Asia (except between NRT and BKK/SIN) and non-stop flights to/from GUM (except between HNL and GUM).
Non-Premier members are exempt from the co-pay when sponsored using miles from a Premier member’s MileagePlus account.
Guess they haven't gotten the message around that elites are exempt from the co-pay.