I am currently level 42 and don’t have plans to grind my way to 50 but I will take advantage of the 3x catch XP especially when I’m already taking advantage of the Fairy spawns for my Platinum medal. It wasn’t until now that I really started to notice the XP difference between the various throws. Personally, I find the XP gap between a Great throw and an Excellent throw is far too big compared to the gap between a Nice and a Great. For reference here is what I recorded for various catches. Note, as this was during 3x catch XP the values are 3x more than normal:
Only curve - 300 XP caught, 60 xp curve, 150 xp first throw
Nice curve - 300 xp caught, 60 xp nice, 60 xp curve, 150 xp first throw
Great curve - 300 xp caught, 300 xp great, 60 xp curve, 150 cp first throw
Excellent curve - 300 xp caught, 3000 xp excellent, 60 xp curve, 150 xp first throw
The difference between a Nice throw and a Great throw is 240 XP (80 XP normally) while the difference between a Great throw and an Excellent throw is 2,700 XP (900 XP normally). While making Excellent throws is very much a skill and should be rewarded the gap between Excellent and Great is too far in my opinion. It feels really bad when you do make an Excellent throw but the Pokemon pops out of the ball and your next throw is only Great or worse.