I increased the dosage today from 30mg to 60mg to see what the difference is. Similarly to 30mg, it didn't make a big difference with R1, still over pretty quickly. However, R2 lasted very long and was finally finished with OWO. There was no chance of a R3 as I was almost at the hour mark after R2, and was spent and satisfied. I believe I could've lasted as long as I wanted in that round so, in my experience, there's a significant difference between the 2 strengths.
One thing to note for anyone taking Priligy is hydration, food and sleep. I'd had 2 good nights of sleep, was hydrated and had plenty to eat - absolutely no side effects today, even on the stronger dose. I'd definitely recommend getting those right if you're going to try it.