If DRS is proving as unreliable as you think he is as a mana source, which is his primary role, the answer might be to cut down on him to put in Llanowar/Fyndhorn/Mystics (Tap-Green or TG Elves) and to put the Taiga in. Producing mana is much more important than machine gunning opponents with drain effects so you go 3-4 TG Elves/1 DRS (still GSZ'able for acces to drain). I have not been experiencing this problem but I've not been playing in a meta full of opposing Deathrites. If the opponent is holding up UU and you suspect Dig is possible it would be preferable to eat a land from your own GY.
I would NOT like this solution because DRS is so versatile but if as hard as you say to produce mana with him it might be the way to go.

