Both of the wired remotes I linked above (DX) can lock the shutter open.

I have the Canon equivalent of the simpler one (no DX back then), and use it a lot for tripod shots.

But I also have a wireless remote, from DX. So far, I use it only for group photos that I am also a part of -- so I can get into the picture too.

The only other possible use I see for it here, might be to get animal / bird shots. Set up the camera/tripod where the beasts roam, and sit with the wireless remote a small distance away.

The wireless remotes are NOT smaller: they require two pieces: one at the camera, one in your hand. And both pieces need batteries.

Cheers