I used to repair fiddles and was deeply invested in the idea of old old wood making better sound, which has some truth in instruments where the wood is the voice. I've owned nearly 200yo fiddles and 5yo fiddles that sounded great. I still consider enough aging to stabilize the wood is essential, but I've had too many recent cut lumber guitars that sounded better than old cut lumber guitars to still buy into that idea. Recycled materials is great though, as long as the materials are good. I can see the charm in barn board/ whiskey barrel/ steam punk builds, but I sure don't want splinters and nails featured in my guitars. Pine is a pitchy wood that seems to stay pitchy for longer than hardwoods take to really dry and season. But I'm not in the group that likes pine for solid body electrics. If I did I'd want pine that had seasoned as long as required for the pitch to stop running. I also used to really be into the fine points of instruments, building and repairing them etc. Now it seems like the music trumps the guitars, as long as they work perfectly. Not that it's not cool to see cool builds, I just want to put my energy into playing music more than chasing gear. I'm glad others keep building though of course. Sustain seems to me to be about a good setup and good technique.