Well the PSG-1 is an actual sniper rifle designed for urban fighting. A SIG DMR is just a battle rifle with a heavier Barrel.True. The PSG-1, while insanely accurate, is really heavy at around 7.5kg empty. The tripod, hendzoldt 6x scope and mount will add another 1.5-2kg. The gun can't be used very well without the bipod/tripod either. Plus ammo. Wouldn't want to carry that thing around. The Sig DMR would be more modular, MUCH lighter (weighs in at 4kg empty), allows more options for day optics, bipod, foregrip, night optic, LAM, etc etc. It'd probably weigh around 7.5kg with all the mentioned accessories and 20 rounds of ammo. The only thing you sacrifice is the 0.5 MOA accuracy of the PSG-1, which isn't really needed honestly. Not to say that the Sig is a slouch; it probably can shoot 1 MOA groups.
Maybe dragnov / galatz better comparison/candidates for replacement?