COPYING A DB From One Server To Another

I was trying to find the fastest way to COPY a 50G DB from our production server to our test server. I was testing this on our test server and had a simple question.

Attach/Detach is out since I can only move not copy a DB using this method.
export/import, bcp and DTS take too long and are not indented for this anyways.

so, I was left with Backup and restore. so, I tried that on two different test servers. Took very long. so, I decided to be brave and try the following.

1. Take DB1 that's running on server1 OFFLINE
2. Manually copy all datafiles and logfiles from Server1 to server2.
3. Attach DB1 on server2.

It came up great. No complaints whatsoever. So basically, it's the same as attach/detach but instead of detaching the DB I took the Db offline and copied the files over. So my question...

Is this supported?
Any chance of corruption on either of the servers?
If a DB is offline, is copying datafiles and logfiles supported (I am bit worried if I might corrupt data in production).
Do people use this method to COPY databases or do they stick with BACKUP and RESTORE?

PS: Are there any other ways to do this?

Thanks so much.