I have used the travel space bags for the last 3 trips and the first trip I laid out all my usual clothes I take for a 10 night stay, I have a list and clothes only for
Disney vacations, and after loading the space bags and putting them in my usual rolling duffle bag, found out I had tons of space left over in the bag. Thinking I forgot to pack all my clothes, I pulled it all out and went over my list. Yep, it was all there, just with all the air out, it just looked like less. Had wife check it out and had to go out and get her some too. Draw back, seeing extra room is your suitcase makes you want to pack more stuff not really needed that you take with you and never wear or use, and this can make that bag real real heavy.
Coming home, I place my dirty clothes in the Disney laundry bags, lay the space bags flat on the bottom of the bag and just cram the laundry bags in the bag on top. Packing dirty clothes in a space bag neatly doesn't save room and, besides, I'm going home, I'm depressed and all my stuff stinks. Give them a try but don't buy cheap, discounted ones, tops don't stay sealed and when the air get back in the bag expands.