[gringoloco]

Blocks will let you have more air pressure in your bags at ride height (basically your bag can be aired-up 2" taller) which will improve ride quality (to a point, after which it gets very firm/bouncy). You want your bags within the manufacturer's recommended installed height range while at your desired ride height. Also with blocks, your shocks are more likely to be in their optimal travel, near center-stroke, versus over-compressed.

I personally would not do bags in stock location without 2" blocks, long panhard, c-notch, and shock relocators. All that said, it's up to you, your ride height desires, and budget, but it certainly won't hurt to have blocks installed as you move forward with c-notch and panhard mods.

Buuuuut (big but), if you are happy with how it feels now, you can probably do without.