I've used a text file with a very similar workflow for a couple years and wholeheartedly agree it's a very flexible and useful tool. The trouble I had was what to do when I'm not in front of my computer. I tried sending myself TODO emails and I'd add them to the list later. That works pretty well. Although typing more than a line on a phone is kinda painful. And it requires the discipline to add the item to the list instead of leaving it in my inbox.

Recently I switched to a physical journal that I carry everywhere. I find a zen like joy in physically writing my thoughts and the portability can't be beat. I do miss the search though. Wish there was a way to combine these two systems without creating more work for me.

Ultimately the best system is whichever one you find it easiest to keep up to date. It's almost like negotiating with my lazy side. "Ok lazy brain, if you're too lazy to keep a list in google docs, let's see if you can get excited about this journal. Look it's got a picture if space on the cover!"