Yes, I understand what you're saying. The key here is that you are not downshifting while braking. What you are doing could just be called shifting.

Heel/toe'ing is required when you want to accomplish the somewhat more involved task of shifting and braking at the same time, unless you have the aforementioned third leg or a pet monkey working the pedals for you. That's why in my original comment I said "it's the only way to get a smooth downshift while braking." Not "smooth downshift a second after you complete your braking"

The problems with leaving the clutch in while you decellerate and not keeping it in gear are: a) It's not as safe. If you need to accelerate very quickly to escape something to the sides or behind you, you can't, because you aren't in gear; b) It causes more wear on the brakes from lack of engine braing; c) It's not as fun! Heel/toe'ing makes you feel like a driving hero when performed correctly d) It takes longer to perform the maneuver. The time may seem insignificant, but on a track if you have 10 corners that require braking and it takes 1/2 second longer each time because you wait 'till you're done braking to shift that's 5 seconds per lap!

 

Regarding "fix-a-flat"...it's a lifesaver (ask any motorcyclist) just make sure you have the courtesy to tell you mechanic or tire guy that you have used it. It's a huge mess for the poor dude taking your tire off the rim.