Sweet! This will make things a lot easier! Who needs to wait for better materials before building when you can make it with a scaffolding block and replace it later?
Yes, this is very awesome. It's one of the reasons why I don't make complex houses made out of advanced materials because I don't feel like having to tear crap down to rebuild it later, nor do I want to go long periods of time without enough housing to get NPCs to move in.
This will also help quite a bit if you are building underground, no more having to mine walls out to replace them with the walls you want, just drop the new blocks in, mine out where you need rooms to go, etc.