So, just focus on getting to where you want to go and enjoy when you get there.
Too many .. just too many people focus on the upgrades and end up having an unpleasant journey.
Most of my upgrades have been on CX and it appears that they occur on flights that are fairly empty in both classes rather than flights where economy is full ... I am a diamond card holder and thus, tend to be high on the list for complimentary upgrades. Many of these have been on short-haul flights in Asia but never on a code-share. If I want an upgrade really badly (example, red-eye or long-haul flights), I call the MPC ahead of time and request to use miles for an upgrade. Unless I have a non-upgradable tickets, this usually works but is, of course, not 'free'.
I love my own bed also... best if its not shared! And Its King-sized and no turbulence!
I am DM too. I normally can get op-up if the cabin I am in is full, but for several months this year (until July) I had very few op-ups. I did get an op-up on a long-haul once out of no reason last year - Y cabin was not full.
I very seldom take codeshare - not even between KA and CX, but that was because of inflexibility. I change my flights sometimes (e.g., taking an earlier flight) and codeshare is not flexibile.
For mileage upgrade, DM is the only tier that CX will consider taking a revenue seat away for an upgrade. CX can normally confirm the upgrade within two days depending on the route. That, however, will only work for the member but not for his/her traveling companion.