Great ingenuity but one needs to beware...
Back in my early Festool days I was a bit concerned about cash flow and used to empty my CTL26 bags and re-use them. I found that after just two goes the micro fibre of the bag became impregnated with very fine dust and I was concerned that the bag could fail - not by breaking apart but by allowing very small particles to pass through.
Even though I am one of the naughty ones who uses a cyclone and drop box I still change my CT bags as soon as it looks as though the outside of the bag is discoloured. With a cyclone that is about every 6 months (compared to 7-10 14-20 bags in that time).
Peter
[edited the bag numbers - I was thinking 12 months for the bags not 6]