I have been sorta following this thread, but finally decided to post. I am a back pack blower freak for lack of a better term. They are one of my favorite pieces of equipment to run. I've owned quite a few, and ran all the top name, top tier BP's in the last few years.
I owned a BR600M (much more blower than the 550 for only a few bucks more) until early last year. Started first pull every time. Light, fuel efficient, and powerful, but the shoulder straps suck. I run BP's in the fall leaf season for 4-6 hours straight without taking them off, day after day. It is a good blower, but nowhere near the best by any stretch. 4 mix technology is not the wave of the future (that came straight from a Stihl
tech rep at our local open-house this year), strato charged engines are.
In regards to the Shindy 802. Paper statistics don't mean much. It will outperform the 600 (though not by a huge amount) as it comes from the factory. It can be easily modded to way outperform the 600 though. The thing about the tubes that has been discussed earlier in this thread being misleading advertising, really isn't at all. They simply do the end user a favor by supplying them with two options for one machine. The larger tube end is slightly lower MPH, but with higher CFM for moving large piles of leaves better. The turbo nozzle forces the air stream through a smaller tip, which raises MPH at the expense of CFM, which is handy for lighter debris like wet grass clippings that are stuck down etc, and for scouring the ground clean of all sorts of stuck down debris and hard to move stuff like cigarette butts. The length of the tube really has nothing to do with the performance compared to the Stihl or other blowers.
I sold my 600 because the year before I bought a new Husky 570 right when they came out. It is the same size engine and same HP as the BR600, but outperforms it by a mile. You'll have to experience it to understand how much. It has the best shoulder harness system of any blower on the market by far. Though it weighs a couple pounds more than the Stihl, if you have to wear either for more than 15 minutes, the Husky is far, far more comfortable. It stays in place on your shoulders thanks to its shoulder straps and cross chest strap design. I know Stihl makes an add on chest strap, but it is junk. I bought one and tried it. The 570 will moves stuff long after the 600 has stopped. We have ran side by side tests time after time on heavy leaf piles and the 570 just keeps on moving them well after the 600 no longer can.
Since Husky owns Redmax (but RM makes the blowers for both companies), the Husky 570 is the same exact blower as the RM 7500, and the 580 Husky is the same machine as the RM 8500, but again, the Husky has a much better shoulder harness than the RM. I have ran the 8500, and while it has more CFM, it doesn't have near the MPH of the 7500/570, and their performance in the real world on debris is very close. The 570 is lighter and uses less fuel, so to me it's a no brainer.
I also use a BR380 for a lot of daily cleanup work while mowing since it is all I need for that type work, and my wife likes to run it in the fall on leaf cleanups when she gets the chance. Those old Stihl 2 strokes are great blowers.
Here is a video that shows what most of the top blowers will do side by side. While it isn't leaves or grass, it is repeatable and fair. the one blower that should have been included but wasn't was the Shindy 802. It would have fallen right between the BR600 and Echo 770 (which is an excellent blower)-
https://www.youtube.com/watch?v=ePqL085xf-g
