If you do one pump you do the other.

Only last night I replaced fuel pumps, filters and accumulator on my W124 260e. Seat of the pants meter is telling me that that acceleration has improved remarkably.

I have not had a problem with cold starts - near instant start on the first turn of the key. A little lag on hot starts. I noticed more of a difference in the start department after I changed the injectors and injector seals .