Bought the new Prolite Plus which has a supposed weight of 22oz, at 1.5" thickness and 3.8 R-value. Slept on it, was decent, but it actually weighed 23oz.
Not a big deal until I saw the 40th anniversary edition, which is basically an improved version of the Prolite Plus. Supposed weight of 24oz., at 2" thickness and a 4 R-value.
I was very pleasantly surprised with the 40th anniversary edition version. The extra half-inch is noticeable for side sleepers like me. Additionally, it had a scale weight of exactly 24oz, so only 1 oz more than the Plus. Additional benefits: the same sticky bottom as the new Plus, a glow-in-the-dark nozzle, cool vintage logo on pad and the included stuff sack, bright yellow color, but also a great addition: a free patch kit. The free patch kit really sealed the deal, as the plus didn't come with one.
Very happy with my pad. Rolls up the same size as the Plus, but more comfortable, more warmth, more features at a slightly higher price. If you could already justify buying the Plus at 23oz, you can definitely (and should) justify buying the 40th anniversary edition too.