Fully agree about "depends on how you measure"--that's kind of my thesis. If you're willing to trade iteration velocity to gain correctness, I would seriously consider Rust, but probably not if the value proposition was inverted.

> But also, I don’t think that “makes you think about memory” is that simple. I don’t have to think about memory in Rust very often at all: that’s what the compiler is for! When I make a mistake, it corrects me, and I’ve only thought about it for a few moments.

Ok, you don't think about it, but the back-and-forth with the compiler still takes a nonzero amount of time that you don't have to deal with in a GC language. At least not until you start to hit upon GC performance issues, at which point the value proposition shifts in Rust's favor, which ultimately brings me back to my point about it being an issue of tradeoffs and my skepticism about Rust-as-silver-bullet.

> I pay upfront with Rust.

But you do pay up front! That's a big deal if your design is not set in stone (which is not a synonym for "prototyping").

I also think this is not a simple question; Rust’s rules provide critical feedback during that early phase. It’s valuable when getting started too. The prototype phase may last slightly longer, but I end up much closer to the final design with its help.

(Again, as always, YMMV.)