I don't have experience with either unit, and since it's December, you may have to wait to hear from someone who does.
However, I can tell you that with SWCG's it's almost always (actually, always as far as I know) better to buy an oversize unit, and turn it down, than to buy an undersize unit. Cell life is a function of 'on-hours', so an oversize unit will last longer than an smaller one.
Corrosion is usually not a problem with SWCGs, though calcium build up may be. However, most units now have double unions, so it's only a 5 minute job to PROPERLY inspect the cells. Clear plastic windows, in pool gear, tend to be not so clear after a short while. Personally, I wouldn't put a lot of weight on that factor.
On the other hand, many cells do fail in less than 3 years, so a 3 year warranty may either indicate the mfg's estimate of likely cell life OR payoff if it doesn't last that long. You can be pretty sure that if most Jandy cells lasted 5 years, they'd offer a 3 year warranty.
Pentair recently reduced their warranty from 3 years to 1 year, because they were having to replace more cells than they liked.
Annual cost of the units is a function of cell life amortization (220 per year vs 550/3 per year), electrical use, and salt use (large at first; large later if your pool leaks a lot). In general, SWCG's are NOT cheaper to operate than a well operated pool using bleach or trichlor or dichor to chlorinate. But they are somewhat easier.
If you want to minimize your operating costs, you DEFINITELY need to purchase a DPD-FAS test kit (like the K2006 linked below) so you can maintain proper chlorine and stabilizer levels. A single algae episode can use a month's worth of chemicals OR MORE. Avoiding those problems pretty much requires following the best guess chart (also linked below) and the using an FAS DPD kit.
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