You can but I wouldn't. Match doesn't store all formats so if you have full quality files it will downgrade them.
Match is more a convenient access service for a person on the go all the time with just a mobile device than an excuse for a decent external hard drive (plus a second one for backup!!).
Using Match as a backup for iTunes - https://discussions.apple.com/message/17039436
https://discussions.apple.com/message/17573191 - "iTunes Match does not properly handle lossless files. If it can match them, you get the Store's 256 version. If it cannot match them, it creates a 256 version and uploads that. Either way, you have lost the benefit of the lossless file."
but a post by Chris CA in 10/2012 says
..."If the songs are not matched, they will be uploaded/downloaded/streamed as lossless." - https://discussions.apple.com/message/19880362
http://forums.macrumors.com/showthread.php?t=1277415 - deleting items from your computer but saving them in iCloud. Yes, but risky.