i find that sometimes bagging is faster, however it depends on what kind of machine you are using. because i remember last year when we got all that rain. just me cut 1 lawn, without trimming, in the time it took 4 guys from a local lawn company to cut, trim and blow the next door house. because they had to double cut and blow. that was at an every other week basis. if you bag there is not that much blowing left or trimming in some cases.
as for putting clippings on a tarp and lifting them. i have one thing to say. i cut a lawn every week where the clippings must be removed. the lawn is about 20M sq. ft. i remove a lot of times, about a yard to a yard and a half of clippings. so that is a lot of weight to lift on a tarp, even with 2 people.