As spectator controls should only be available for spectators there need to be no worry about them covering other useful keys (like shift+1 covering secondary weapon key).
How I would want it to be, is to have the 0-9 keys to be beind able.
Shift+<key> sets a player slot.
Ctrl+<key> sets a camera position.
<key> goes to either player or camera position.
To put it in an example.
Lets say there's a 3v3 CTF game.
I start off with hotkeying the players, so I'll be using the Shift key.
Spectating the first player, pressing shift+1.... there after goes trough all the players and marking them with shift+2, shift+3, shift+4, shift+5, shift+6.
- Now I have all the players hot keyed.
I might also want to set a camera position somewhere on the maps, lets say at both flags.
So, I move my view to the alpha flag, and then I press Ctrl+7, then to the bravo flag, pressing Ctrl+8.
Now if I want to view the first player I'll press 1... to then view the bravo flag I'll press 8.
Though, I guess it could be possible to bind any key. But at the very least I'd love to have the 0-9 keys bindable.
However, these controls should be automatically disabled when you open the chat, and enabled once you close it.