Is there significant quality differences between DIY mini splits (Mr. Cool, Pioneer) and non-DIY mini splits (Mitsubishi, Daikin)?
I'm going to replace 4 window and portable AC units with something more permanent, because 2 are under-powered and only one provides heat. Thinking of installing 4 single-zone systems because only 1-2 would need to be on at the same time, and it would simplify installation a bit.
I will be diy-ing regardless, so I would prefer not needing to buy extra tools and refrigerant from shady suppliers. But, if non-DIY systems are significantly better, that's a trade-off I'm willing to make.
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.
I was able to buy some R-410a on eBay when I installed mine a couple years ago. Looking again, I don't see any more listed.
The tools weren't too expensive. I wasn't able to buy lineset covers locally, and I'm sure I paid a little premium buying them online.
I wasn't able to do a high pressure leak test because I was only able to get a low pressure nitrogen regulator. I ended up tearing my hair out for months because the system barely worked because there was a leak I didn't find until I noticed oil on a fitting.
Having a recovery pump and cylinder would be invaluable for troubleshooting leaks. But they're so expensive.
Agree a recovery pump was a big help. I already had a powerful vacuum pump, but I did buy a recovery pump, cylinder, gauges, and a scale.
You can still check for and find leaks with Better Bubble or similar leak detector.
These are also great to help prevent leaks if you don't have Nylog and a torque wrench/crowsfoots for the fittings. They're Teflon or similar. https://flareseal.com/