Grado can make a great cartridge, I do not think they enter their own until they get away from elliptical styluses.
I owned a 103 and like the Linn LP 12 everyone wants to make mods to them because they are all over the place and dirt cheap. In its day it was a good cartridge. Today it is just a platform for everyone to screw around with. If you can not pick up the difference between any modded 103 and say an Ortofon Verismo either your system, your ears or both need work. The first thing you will notice is the Verismo will be MUCH quieter due to its stylus profile, then sharper transient response due to its diamond cantilever.
The Ortofon 2M Black LVB version is superior to any Grado at or below it's price point. There is no, let me repeat, no $1000 MC cartridge that can compete with a 2M Black LVB cartridge.