Haha.. seems the stories are similar.
First time I bought MBP 13" 2015 and I really loved it but after some time I need more performance, thus I decided to buy 15" 2015. I've bought it with dGPU and.. it's pretty awful. The throttling so huge.. and the fans almost the whole time is soundable (I just got used to work in silent with my old MBP 13" 2015).
And when I was playing... for example, in CS: GO, the FPS could be decreased to 50-70fps (from 150+), but with iGPU I have stable 80-100 the whole time. However, games is not prior tasks I'm doing on my laptop
It was just like experiments.
Thus I decided about.. why I need dGPU? It is throttling toooo much and I have annoying noise the whole time.
Then I just sold it and buy the same laptop with iGPU only. And I'm pretty happy. It is silent the whole time, I'm not concerning about whether I'm going with dGPU or iGPU (because it could be switched almost randomly), and a lot issues with stuck on dGPU after disconnecting external monitor. Google Chrome can randomly enable dGPU (for example when you're going on google maps, or other activity).
I understood one mandatory thing: MacBook with dGPU is not worthy completely. It has annoying noise, huge throttling.
And "iGPU <-> dGPU" auto-switcher is awful, I'm not able to run only with iGPU when I no need huge graphics performance and the external monitor is always connecting to dGPU (because of circuit design). It's completely not convenient (especially for me).
In this case I like how this technology made on Windows where I'm able to select exact application to run with dGPU (or eGPU).
(BTW: when windows laptops will have a great trackpad I'll sell my mac forever
)