One thing to remember about modular helmets is they are usually a good bit larger than a standard helmet. (Physical size wise) I wear an XS helmet, all of the modular helmets I tried on I felt like a bobble head. Most of them only come in one shell size.
Just another thing to consider.
This past season I tried on, and purchased a ton of helmets. After my bad crash last season I deiced to retire my Suomy Vandal. One of the lightest helmets out there for the price. It was annoyingly loud. Even with ear plugs in.
After owning 6 lids, and trying on probably 25+ I went with an XS Qwest. Shoei makes some of the best helmets out there. Latches, detents, vents, liner, visor quality, you name it. I think anyways... Made my Bell RS-1, Shark RSI and Vandal feel like toys.
Look into the Shoei Multitec, it is a bit older. But you can find them for great prices on ebay brand new. It is pretty light too!