By any chance are all the headquarters of department store manufacturers located in Pampanga?
This would explain their magnification promise of 600x imprinted on the box.
A 3" apo has an exit pupil of 0.25 at 300x.
Pampanga is me. Good seeing here, too.
I agree, a less than 0.3mm exit pupil is problematic for a whole range of objects. You can do doubles easily enough, and the moon should be very dim. Depends on the planet, it may be sharp at the limb but you can bet most low contrast detail and probably color are gone. A good refractor will have better throughput, I suppose that allows a little smaller exit pupil than a CAT. But, IMO, 0.3mm doesn't have a lot of utility. It's not the scope, the image is still as good as it is at 1mm exit pupil, but the eye begins to fail at small exit pupils on most things other than high contrast double stars.
"My very good SW150 Mak would do 600x on doubles and the moon, the moon was dim but still sharp."
This is my experience, too. Doubles are no problem. But the moon is dim with noting more to see up that high.
"350X on Jupiter was easy. Past 400x and Jupiter gets dim in the Mak."
I spent years observing Jove exclusively. About 240x (~0.6mm exit pupil) range is the best I could do on Jove. By 0.5mm exit pupil, the fine detail is washed out, but the broader detail (belts and zones) are still visible. Again, it's not the scopes fault. It's the same nicely resolved image we saw at 240x, but they eye struggles more when the object is dimmer.