So currently I own the FX Crown with the .30 caliber barrel. Here are my thoughts in no particular order as it relates to the .30:
1. I live on a fairly exposed hill... there is ALWAYS wind... it is rarely dead calm... as a result I have gone towards .25 and .30 to buck the wind better. I know-why not slugs? Well currently for the distances I shoot 25-100yards slugs are (at the present time) too expensive to justify killing pest birds... but as Matt Dubber pointed out in his last video, that is quickly changing... I don’t expect them to be as expensive in the next year or two.
2. Pass through is a valid concern but I think the concern is valid for .22 as well... I own a .22 Daystate Airwolf MCT and at 29ft lbs on low power I have had pass through with round nosed jsb 18.13 pellets...That being said, the risk is much greater with .30 as it is retaining more energy at 100y than .22 has at the muzzle.
3. Shot count- .30 GULPS air...I get 35shots before I have to refill. .22 and .25 are much more economical... If you’re looking for a gun that you can fill on Sunday and shoot all week, a .22 or .25 might be a better choice.
4. I like the flexibility .30 gives me... I can shoot anything from a starling to a Coyote at reasonable ranges and not have to worry about an ethical kill as long as I put the shot in the right spot. Now, as high power .22 slug guns begin to sweep the market, I’m sure there will come a time where a 60ft lb .22 slug gun will cover the range of starling to coyote but as I said before... until I shoot farther (more than 100+) and the price drops on slugs, the .30 will be my go to gun. Note: in many states a .22 (slugs or not) is not allowable for certain game, so make sure you check your laws first.
Just my thoughts... .25 is probably the sweet spot... but the .30 is damn accurate and man does it pack a punch. Good luck with your choice!!
Sharkman