My searching has come empty, but I would like to pass something by the collective brains over here. I will be flying again SFO-YVR-SFO on AC metal and therefore have a choice between purchasing the trip as a 014-ticket AC "S" fare or 016-ticket UA "W" fare (codeshare) for the same price.

Fare rules are very confusing, as usual, but I seem to understand:

Guaranteed air fare:

• AC: none; if fare drops AC keeps the difference
• UA: difference in fare credited as a non-refundable MCO (voucher); no service charge

Unused ticket:

• AC: may be rebooked (minus $100 fee)
• UA: value can be used towards purchase of new ticket (minus US$150 fee?)

Ticket changes:

• AC: fee is $50 per segment, will reprice to fare current as of change request and if it's lower they won't refund (or take the $50) difference
• UA: fee is $150 per ticket, repricing is not needed as long as original booked inventory is available; if repricing is advantageous and fare is lower they will issue a credit for the difference and/or the change fee can be taken from the credit

Standby (free):

• AC: not allowed
• UA: rules don't say

Confirmed same-day change (paid):

• AC: $50, airport only
• UA: rule only covers UA metal (US$75); AC rules apply??

OLCI:

• AC: yes
• UA: yes, may require having to call AC to get their record locator, although 016- ticket number should work

From a United Mileage Plus credit standpoint either ticketing earns 100% credit.

Is there anything else of importance that I am missing?