Here are both the tubs you said you are looking at. It is from the Jacuzzi brochure. Hopefully you can get a few of your questions answered by looking at the numbers here.
J-355
Seating Capacity
5-6 Adults
Dimensions
91 in x 84 in x 38 in / 231 cm x 213 cm x 97 cm
Average Spa Volume
330 US gal. / 1,249 Liters
Dry Weight
882 lbs. / 400 kg
Total Filled Weight
4,927 lbs. / 2,235 kg
Pump 1
North America 2 speed, 2.5 continuous hp (4.5 brake hp*)
International 2 speed, 2.0 continuous hp (3.0 brake hp*)
Pump 2
North America 1 speed, 2.5 continuous hp (4.8 brake hp*)
International 1 speed, 2.0 continuous hp (2.6 brake hp*)
Circulation Pump
Yes
Diverter Valve
2
Filters
2 - 60 sq. ft.
Electrical North America
240V 60 Hz @ 40A, 50A or 60A
Electrical International
230-240V 50 Hz @ 20A, 30A or 40A
J-LX
Seating Capacity
6 Adults
Dimensions
84 in x 84 in x 36 in / 214 cm x 214 cm x 92 cm
Average Spa Volume
360 US gal. / 1,363 Liters
Dry Weight
894 lbs. / 406 kg
Total Filled Weight
4,730 lbs. / 2,146 kg
Pump 1
North America 2 speed, 2.5 continuous hp (4.5 brake hp*)
International 2 speed, 2.0 continuous hp (3.0 brake hp*)
Pump 2
North America 1 speed, 2.5 continuous hp (4.8 brake hp*)
International 1 speed, 2.0 continuous hp (2.6 brake hp*)
Circulation Pump
Yes
Diverter Valves
1
Water Purification System
CLEARRAY®
Filtration
ProClear® Filtration System with skimming weir, increased filtration coverage, and Debris Catching Bag
Filters
2 - 75 sq ft
Electrical North America
240 VAC 60 Hz 40A/50A/60A
Electrical International
240 VAC 50 Hz 20A/30A/40A