I faced a similar decision, except that because my TG gold had a lot of life yet (another 2 yrs from this Nov), I decided to go with the most generous points earning FFP instead - which was BD (because I fly C where poss).

I redeemed a ticket with BD the other day, on LH metal from KWI to INN and it was such an easy process. I later had to cancel, and again - such an easy process. Miles returned, CC re-credited, all for the cost of a $50 fee. I also like the way on BD that you can book one way for just half the points, and if you don't quite have enough, you can add some cash to your points, at very reasonable (IMHO) rates.

I was going to start putting points back into ROP in November, to re-quality 2010-2012 but to be honest, with BD earn rates TG can keep their 1 free upgrade.

You raised a valid point about LH though. It all seems up in the air, but worst case is that you'll know in advance of any M&M takeover of DC and can choose to burn the points earlier on. But in terms of status, again - worst case - you'll be transferred to SEN at least for the remaining life of your DC gold.