I am not part of DJMR, so whilst I'm vaguely aware of the different transfer rates I can't easily check the current situation. I'm somewhat surprised that DJMR is transferring to HH at 1:1 as this would be the same as the standard Amex MR scheme .. when I last looked at DJMR it was, as you have suggested, 1xDJMR=0.5 HH.
SPG transfers to VA (but not QF) at 1:1, so, if 40,000 DJMR = 20,000 SPG, then, this could work in your favour if you wanted VA points, because I believe SPG will award 5,000 bonus points upon the transfer of 20,000 points ... so, 40,000 MR = 20,000 SPG, transfer those at 1:1 to VA and gain another 5,000 SPG at 1:1 = 25,000VA points in that transaction.
If you were to transfer direct to VA from DJMR then you'd only get 40,000DJMR = 20,000VA.
If we were after QFF points, I think there is an option to direct sweep (not transfer) from the DJ rewards scheme to QFF at 1xDJ reward=0.75QFF, so 40,000 earned DJ rewards (not MR) = 30,000 QFF.
Depends a lot on what you are trying to achieve. If you are about to cancel your DJMR card and need a safe haven for your accrued points, and if transfer to SPG is 1:0.5 then that seems like a reasonable way forward that still allows some flexibility. If you are keeping the DJMR card and really want QFF points then you are probably better off transferring your DJ rewards points to QFF via direct sweep rather than having those DJ rewards end up in the DJMR scheme.