In answer to the OP, I do use 102 cards to sort/store some of my collection.
I find the re-shuffling in stockbooks a pain as well sometimes.
I don't leave them in the red boxes though. What I have found to work for me is to use the manilla (cardboard) pages with slots. I then place the 102 cards in the slots in a way that allows the stamp(s) in each 102 (or 104) card to be visible on the page. The card can also have a description of the contents (including variety info, date, city, etc. - always in pencil so it can be modified)
If I ever want to sell/trade the item, all I have to do is remove the 102 card and all the info stays with the item(s).
If I add an item, yes I may have to move one of the cards over or down, but as there are maybe 8 cards per manilla page, that is not difficult. These can then be put in a nice binder.
An example would be my Canada Map stamp collection (sorted by plate and position #)
I also use photo albums to house the 102 cards. Again, the info is on the card and if it is moved, the info stays. I leave some empty Pages if I know I will need to add missing items. The ideal photo album has removable pages to make this easy. I house my RPO (Railway cancel) collection this way. One album for each area of Canada. Sometimes the 102 cards slip out, so you need to find an album with the correct size of plastic sleeves (eg. 4x6"). You can often get them with nice binders at a fraction of an album/binder cost (with the pages already included).
The other nice thing about the 102 cards is that when I wish to sell an item, all the info is there and it is easy to scan (without having to remove the stamp. I scan a bunch of cards (say 8) and then crop the stamp image. I like the black background cards for some stamps, for others, the white background shows best - depends on the stamp/cancel, etc.)
The only drawback to this system is if you have 100's or thousands of a certain collection. It would require too many manilla pages.
Here is a picture of a 102 card I found.

Here is an example of a manilla page. This is not one of mine though. I don't like how the manilla pages hide the bottom half of the stamp. Not ideal for scanning purposes as I like to show the entire stamp (unless it is a large lot of common stamps).
The bottom row shows how a 102 card with stamps can be inserted and still show the entire stamp.)
