My understanding here is that it's a pretty simple tradeoff. If you're flying LH metal and have a LH flight number, then you /might/ be able to upgrade with a SWU or (for certian fare basis) miles. If you're flying LH metal on a UA flight number, you get the UA mileage plus elite mileage bonuses, but there's no way to upgrade.

Note that the upgrade process on LH metal/LH flight number is NOT smooth. It requires you to have your upgrade instrument (SWU or miles) converted to a paper certificate and then mailed to you. If you want a confirmed upgrade (ie, with miles, not SWU), then a "virtual PNR" is made by UA reservations which is an upgrade request that gets queued over to LH. It then takes LH 1-3 days to read this and respond. If LH doesn't clear it right away, they simply send back "NO". If you still want to try, you have to call UA and ask them to send it over again. There is NO waiting list that these requests go into ... it's simple a question asked and answered. So you just need to keep calling.