Perhaps a magnitude more effective than copy/paste, perhaps not. But do I get more than $300/month of value from it, per developer? Almost certainly.
The bottleneck was already checking the work for correctness and building my own trust / familiarity with new code. So it's made that problem slightly more pronounced, as it generates more code faster, with more surface area to debug when many new changes arrive at once.
You described the price increasing from $10/month to $300 (which is an order of magnitude). What I meant was when you are saying it equals out (in terms of cost for you) you would expect a similar increase in performance. If that makes sense.
Still worth it, but that’s a big jump.