If a conversion is done properly, you will barely notice the difference in cooling ability. I live in Florida, have no tint on my windows, and my converted system can get the cabin down to 72 on the hottest of days. Colder if I choose. That’s with all original factory installed parts, just with converted refrigerant. R134a (the new stuff) is better for the environment, cheaper, easier to obtain, and DIYer usable.
Make the switch.
I’d also suggest seeing if you can get a lower price on the conversion. You might be able to get it closer to 900 or 1000 if you look.
-Matt