Chigoogs:
In general the Palermo is a larger spa by 7 inches. I wouldn’t worry about the jets being ball bearings because every manufacturer uses ball bearing in their pulsating jets (except for Sundance).
I would expect the Palermo to be less expensive than the J-355. The Palermo has less of a warranty than the Jacuzzi J-355. It has a three year warranty on the pumps, motor, heater, and electronic controls. The J-355 has a 5 year warranty on those items. However, if you removed the front panel from both brands you will see that the pumps, motor, heater, and control panel are the same in both manufacturers. However, the Palermo has the exact same warranty on jets, cabinet, and stereo (if you get one).
The Palermo has better filtration than the Jacuzzi Premium. It has better filtration because of the weir door that Sweetwater uses. This allows you to not expose the cartridge to the rest of the spa when cleaning. In the Jacuzzi, the cartridge will be exposed to the rest of the spa. I recommend you to remove the cartridge in both brands to see what I am talking about. Nasty stuff just falls out of the cartridge. You can also try to ask the dealer to upgrade you to the Sundance filtration.
Any more questions ask away.
Chris