Design help with typography about mui HOT 3 OPEN

This is just my personal opinion, but since no one else has responded, I'll throw in my two cents. I much prefer the extra spacing of the top button in your example, and I think that it works fine with Helvetica even if it wasn't designed for it. I would keep the font spacing.

As for the font smoothing, I was about to say skip it, but after looking at the comparison images you posted I have to say it looks much nicer in some ways. I think that the 3rd button down is the best looking one, but I'm worried about ti making text look too thin. I don't have a strong opinion either way on that.

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Personally I think the smoothed fonts look worse for some reason and the wider spacing looks better.
Can you not use Roboto?

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Adding a custom font to the CSS affects the load time of the app and the choice of font will have big effects on the look and feel of the site so we wanted to hand over control of that decision to the developer.

Also, it's easy for developers to add a custom font themselves so we didn't feel that we were adding much value by embedding it in the CSS. Here's an example of how to add Roboto:
https://www.muicss.com/docs/v1/css-js/boilerplate-html

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