I found straps to be plenty good without drilling. I just couldn't bear the thought of marring that piano black finish, tho I'm sure you can do it and have the end result look nice with a little care.
I tugged on 'em and jiggled 'em around pretty good. They're no going anywhere. I used some inexpensive nylon straps that came with a tent I think... Anyhoo, another thing I like about the sharper angle is it moves the rear port a little further out from the wall too.
*Edit: Also, I had that one down recently when I did my Ultra/TP160S shootout and checked (with a little anxiety, lol) for any scuffs or marks from the straps and am happy to report there were none. Just be carful not to let the straps move or slip when you put everything together.