I've lowered my monster 620 almost 2 inches. I'm 5' ziltch.
I have shaved my seat as well as lowered the bike. I can now get the balls of both feet or toes down, depending on which boots I wear. (I'm now ready to raise the bike up a bit.)
Before lowering the bike I suggest shaving the seat. Get a stock seat from a dark model which has a lower seat height, and shave the seat, a local auto upholsterer should be able to do it for you rather inexpensively.
If this is not low enough, then get an adjustable ride height rod. Can buy this aftermarket or your dealer should be able to find one for you. To lower the bike, the stock unadjustable ride height rod will be swapped for the adjustable one and lowered. You can lower the bike about 1.5". The front end will then be lowered to match the rear. After this is done, DON'T FORGET TO SHORTEN THE SIDE STAND. Many forget about this. My dealer cut and re-welded mine when they lowered my bike for me. The bike's handling should be fine as long as the front and rear match. The only issue is ground clearance, riding a lowered bike means you have to pay extra attention to pot holes and speed bumps!! I actually had a friend weld a mini skid-plate on my lower header, and I've been known to give spark shows now and then. I plan to have custom headers made to increase ground clearance (if I can get my bike working that is.... ecu problems right now

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I also suggest having frame sliders installed, doesn't hurt then if the bike is dropped at a sudden stop.
Best of luck.
Michelle