Actually, the booklet printing is a function of the printer, usually. It has to be able to do double-sided printing (even if it's manual - the concept has to be in the printer utility).
PDFs can't yet replace printed copies for me. But, they are getting close.
Not on the mac side. It's built in to acrobat reader. It wasn't in older versions, and may not be in other systems. I do have to flip the pages, and run them through again, but the rest (including ordering them correctly) is handled by acrobat.
Icosahedron:
PDF is intended to be printed locally for such purposes.
Another nice feature: for MoTrav PT Draft 1, I printed 3 copies for player use: 1 full copy, and 2 with just CGen and Tasks.
All:
PDF's have actually created a whole new avenue for gaming purchases. It's really looking like PDF is keeping several "discontinued" systems available. Like CT, MT, TNE, T4, BTVS, Classic D&D, Old D&D (BXCM), AD&D1, AD&D2, CP2020, MektonZ, Earthdawn, Battletech... and more.
It is a viable means, and given the impending SRD for MoTrav, may result in a variety of Traveller variants available in PDF.
Note that the MRQ SRD has not resulted in large adoption of the MRQ engine, but has resulted in a few. (GORE, for example.)