Fall of Delta green is awesome! But you're absolutely right that gumshoe is less awesome. I really hope trail of Cthulhu second edition creates the necessary changes that allows me to love gumshoe because I really want to like gumshoe more than I do.
I picked this up years ago. I loved the old Pagan Publishing Delta Green stuff, and liked the idea of expanding this part of its history. System-wise, I'm sure I'd just use Call of Cthulhu. I used to feel uncomfortable deviating from the rules as written, to the best of my understanding. But with Call of Cthulhu, I've gotten better about making sure a failed roll doesn't stop the investigation in its tracks. A failure brings complications, or problems. But it doesn't stop the flow. I'm torn on Gumshoe. I read a very trimmed down version that I really liked, but when I read (1st Ed) Trail of Cthulhu, it felt very clunky. It was maybe a bit better in The Yellow King. But I'm still not sold.
Anyone have a spot hidden of 50 or higher? Okay, this is what you find. Not too difficult to house rule cthulhu, and delta green is so well supported but the lore is so tempting.
I think Gumshoe is sold in a bad way when they push the "automatically get clues" thing. It is usually how people sell it, even Pelgrane Press, but as you say, that's easy to work around in other games too. And Delta Green also has mechanics for automatically succeeding when you're doing investigation. The big difference with Gumshoe as opposed to BRP is that you play as a much more competent people in Gumshoe. Gumshoe is more cinematic, while BRP is more simulationist. In CoC or Delta Green you have lots of skills where your value will be around 5-10 % and if you have 50% in a skill that's considered really high. In Gumshoe you have around 50% chance to succeed in most rolls even without spending your points. If you do, you can very quickly get to 100% chance of success. It's more cinematic, and spending points is kinda interpreted as taking the spotlight. It's a very different game system from BRP, but I think the core difference isn't the automatic clue gaining, but how skilled your characters are, and that you can spend metapoints to basically guarantee success if you like. That changes the feeling of the game a lot.
