Lightening the flywheel is one of those mods that works different on different bikes.
Now on the VTR it is a mod with very few downsides as IMHO the bike comes with an overly heavy flywheel stock.
Again IMHO this was done to tone down the bottom end for the "average" rider.
Ask anyone who has installed a lightened flywheel and they will tell you the bike has no issues what so ever of flipping over on her back if you get hamfisted in 1st, even with stock gearing.
Have a basic motorbike skill set and this is no big deal but we are talking the "average" rider and Honda just wanted to cover their butt.
If you look at a basic (or Moriwaki Spec) lightened flywheel you will see that it looks surprisingly like a stock SP1\2 flywheel.
What I have found after running a lightened flywheel for at least 10yrs now is this:
Downsides-
The bike can and will hurt you if you don't respect 1st gear.
There are a bit more vibes if you let the carbs go out of sync.
and that is about it.
The plus or minus depending on your riding style is an increase in engine braking.
For this you get better throttle response which in performance riding allows you to do many things.
So I have to say the lightening then flywheel is one of those mods with no real downside and it really does make the bike more fun to ride.

Loud pipes don't save lives, knowing how to ride your bike will save your life.