I'm Bleeding
OK - think about this: PLEASE READ
The brake fluid has been captive in that system for years and is picking up moister (#1 killer or brake system) and debris from the deterioation of fluid, hoses, seals and pistons.
It is Highly recommended to bleed the system yearly to keep it healthy.
As mentioned, it is not a good idea to force all that crap back into the master cylinder as it can lead to master cylinder failure.
That being said you can take a functional system and ruin it by shoving the old worn out master cylinder to the floor during the 2 man manual bleed process. Or forcing the nasty old fluid back into the reservoir Why?
Because the system has not seen the full length of travel (master being pushed to the FLOOR COMPLETELY) and the sediment at the end of the bore gets trapped in the rubber piston. No it dosen't fail immediatily, but it may cause the master cyl to fail shortly there after the brake job is completed (month). Does this make sense?
Most DIY do not bleed the system and if you have never done it before, have a proffesional do it!
If you plan to do it, you will need a helper. Also - although faster, it is not required to push the cylinder completely to the floor (no mans land for all the sediment). This will take longer, but unless you plan on returning, resist the temptation to push it to the floor during bleeding or you will be returning to replace the master cylinder.
If your cylinder is new, no worries - push it down all the way. Or you can pressure bleed by forcing the fluid through the system (special hardware required) and cracking each wheel bleed to get the new fluid through the system and displace all the air and sediment.
Thats why the boys at Les Schwabies give you the high bill. That can't afford to take the risk of having a system failure, so they go the safe route and replace the master cyl, calipers and wheel cylinders (if not 4 wheel disc).
PS - A NEW MASTER CYLINDER IS CHEAP INSURANCE!
Nice Book Eh? SAFETY is Must and I hope this helps.....
EDIT: One last thing - before those of you with deep pockets go out and buy the cross drilled rotors, DO LOTS OF READING and look for key words like "Cracks"/"Warp" ect. Yes, they look Kool but most are not meant for street use where they DO NOT GET INPECTED REGULARLY!
/Randy