If you're 2P, I'm guessing you don't have any SWUs. So you can only upgrade using miles, which will cost you 30k each way on an H fare. I consider that a pretty bad deal, given that a saver R/T in C runs 80k miles.

If you don't pay up the miles you'll be stuck in coach. In that case, UA E+ is a much better choice than LH Y. On the other hand, MUC is a really nice airport. So if you're willing to spend 11h with less legroom, flying UA one way and LH the other might be another solution.

LH also has much better (and free!) beer though