I've got no idea if Chaosium will release a .pdf of BRP, but I certainly hope so.
Up until the beginning of 2007, I was typing up my notes and adventure materials on my desktop, printing them out, and bringing a mini-DVD/CD player with speakers to game sessions to use for musical accompaniment.
Then, after the baby arrived and I lost my office space, I moved primarily onto my laptop. Racked for time, I was often scrambling to type up my notes up to five minutes before leaving for game sessions. Then a switch went off, and I realized:
"Hey, we sit around BSing for the first half-hour waiting for people to arrive.... I end up making notes all over my printouts... and it's a pain in the ass lugging the DVD player, speakers, and all those loose CDs. My laptop holds all my notes, itunes has all my music and integral speakers, the screen doubles as a GM screen, and I can even do stuff like Initiative and HP as simple docs rather than a lot of scratch paper. Plus, I can instantly look up stuff on Wikipedia if there's a real-world question I can't answer on my own!"
So now, I generally do all of my prep on my laptop, and take it to the game. I save the relevant files onto a thumb drive and email them to myself as backup, but it's worked like a charm.
So I buy any rulebook I can in hardcopy and .pdf (if available), if I'm going to be running it more than a half-dozen times.