Anecdotally only, I know multiple people who have done the Mr. Cool DIY kits who have had issues ranging from minor to catastrophic. Some may have been installer error. Some were defective parts out of the box. Regardless, the parts are generally way more proprietary and often only available from the manufacturer.

I decided to go with the more commercial systems and just DIY'd 2 Daikin setups, one 3 ton/4 zone and one 5 ton/5 zone.

You will absolutely need certain somewhat specialized tools. I went as far as to get my EPA license to be able to purchase 410a from reliable channels. Overall the cost was still way less than what HVAC contractors are getting these days.

This is only anecdotal I know, but I am very happy with how the diakin systems have performed.