Recently I purchased Electri6ity, an electric guitars' sound library. It requires velocity value (under 90 or over 90) for some keyswitches to make sustain, mute and half-mute sound. These "velocity for keyswitch" features couldn't become mainstream, but in some areas they are must-have. The soundset for Sibelius and Electri6ity already exists, and I tried to write VST XML for Overture and Electri6ity, but came to a standstill. Hopefully Overture 5.1 will have this feature.
Overture 4, Sibelius 7, Notion 4, Cubase 6, Sonar X2, Studio One 2 Pro
Windows 7 x64, i7 2600K (@4.4GHz), 16GB RAM, MOTU 828mk3