I believe the claim of 95% UV reduction. That's necessary to protect the covering itself. The coverings lacking a UV blocker are destroyed in short order. The only disadvantage I've heard about is bumblebees may not do as well under some coverings due to light exclusion that they need to navigate. I don't think lack of UV will affect plants. But greenhouse plants still might need some hardening off when going outside.

No direct IR simply means as you suggest that it has been diffused. This might reduce heat stress on some plants but I've not seen much damage under clear polycarbonate with 90% transmission.

Max heat gain by day will likely translate to max heat loss at night. In my climate two layers inflated of woven poly reduces both heat gain by day and heat loss at night. A plus here but we have lots of sunny warm days all winter..

The covering for my greenhouse is clear - you can see through it easily. The covering for my high tunnel is opaque. The clear covering does heat up faster, but I'm not growing in the dead of winter. On a typical spring day, the difference will be that the greenhouse gets too hot and the high tunnel is just about right. The opaque covering also helps tomato fruit not get sunburn.