Have you tried just making an Americano? Im a fan of strong coffee and thats what I do in the mornings.

That's just way too much caffeine. My normal morning coffee is 10g of beans in a single shot.

Sigh, stupid Imperial units.

354ml of coffee is quite a bit, even with strong robusta local coffee I don't do more than 180ml on average, and 4-5 shots sounds like a lot. I suppose if your body can take it, that's fine, but I do wonder if it'll taste like ass after an hour or so; won't it get cold?

I mean, it's just a lot of caffeine. I'm sure some people have no problem, but others will be off the walls or just sick. What's your typical caffeine intake? If you just want a hot drink to sip on for longer, try a couple shots of espresso and top the mug off with hot water for an Americano.

That's around what I do, either at home with my Aeropress or when I go to my favorite coffee place, a six shot iced espresso.

I only feel jittery if I drink too much at once, and almost never want more.

Of my at home mugs, sometimes I'll have a second but not always.

And I don't have any problems sleeping.

Don’t hurt yourself there!

My regular morning brew is a 300ml moka pot in a mug with frothy milk. According to this I'm taking about 516mg of caffeine each morning, without spacing it out.

I have owned that thing for over a decade and have always treated it as a single serving device. I think FDA's wisdom is mostly a guideline, and nothing beats simply knowing your own tolerance.