Sunsilver, you won't break the guard hairs if you use it correctly.

One should use common sense when using any tool. Comparisons:

(1) If you use a #40 blade on an Oster clipper for a surgical prep, you can cause big time clipper burn--if you use it incorrectly. Actually, I clip the hair on the bottoms of the dogs' feet--gives a cleaner appearance--minmizes mud tracked through the house in rainy months.

(2) I use a Dremel tool for trimming the dogs' toenails. Again, if used by an impatient asshole, the Dremel can leave the dog a bloody mess.

(3) I also use an e-collar for fine-tuning the training on my GSD's--a very effective, humane tool in the right hands.

I have one and love it. However you must use it exactly like Louise said,

"Just drag (using very little pressure) the tool along the coat--in the direction that the coat grows".

Love mine.  As said above... don't dig... use short light strokes.  

I use to use 3 brushes (slicker, shedding blade and rake) when grooming my GSD.  I bought my first FURminator a few years ago and never looked back.  As a test, I used the 3 brushes above as normal...then I went over my GSD with the FURminator and watched the fur fly.  I would caution though if you do decide to use one be very careful initially - the blades can be sharp.

The handle broke off of my first one after 2 years.  I ordered my second one off of eBay for like $34 (much cheaper).  They're selling them in the stores for $54.  I use the largest size - still looks small when you receive it compared to the other brushes but it is effective with the fur.

I use the medium size one.  It can work around the legs much better with more control.

I love the furminator, I bought mine for $25 on eBay!

I love it and hate it at the same time

I love it because it takes out a lot of the undercoat and it does help to prevent the constant shedding of the dog.

I hate it because the tips are sharp and therefore you need to be very careful about putting pressure down on the rake. If you put too much pressure you will cut the dog including yourself, if you accidently rake your hands. I've notice that it breaks the hair ends of my dogs coat  when I use it, as what K-9mom mention on her post.

I have the large size rake.

I have the medium one, hubby just filled the yard up with Kali hair this AM, the FURminater works very well, her coat looks great; as previously posted, just very lightly stroke the dog in the direction of the hair, & you won't believe how effective it is! A real vacuum saver when it's time to blow the coat! And she backs her butt up to get groomed when we use it! Well worth the $$! jh

OMG

so pleased it works wonderfully

thanks for all the help and advice.

didn't lose hardly any guard hairs and all the dogs love it and they look great.

my hoover is now in hibernation