Ben - your assessment is helpful, but I think in the real-world - there are other considerations that warrant a closer look, and I think you some of your points might be inaccurate or misleading
I own a Kodiak - and it's been rock-solid for me - but from reviews it seems that the Apex was a step backwards in many ways. While it's worth knowing the faults of the Apex - it seems the Flex is replacing that unit in part to address those shortcomings. And while I don't own a Titan - I've used one, it's great - and I've debated buying one - so I'm no "fanboy" on either side - just trying to offer some perspective.
Battery- I haven't seen anything referencing 80% usable capacity on the Flex batteries. Given the intense scrutiny on Inergy's past spec claims - I think they'd be up front on this (rather than get caught) if this were the case. Inergy is also stating 2,000 lifecycles - not sure where you are getting the 500 claim from. (and a 10-year battery replacement warranty). And a Flex with a 2nd battery is ~2138wh - a bit bigger than the Titan - plus you have the option to save the weight/bulk if you don't need both all the time.
Charging: The Flex is 30a max charging, the Titan is 40a. Many folks don't need to fully dis/charge their unit daily so ~400 watts of solar input is pretty solid.. You don't
need to buy their additional supercharger and all that cost unless you are really doing heavy-discharge, daily use with multiple additional batteries. Also at 24v - that Titan would require at least a pair of common 100w panels - vs just a single panel for the Flex. For casual users or portability - additional panels add up.
Size & Weight - 70lbs for the Titan, vs 30 lbs for the Flex. Even adding a 2nd Flex battery takes it to ~45lbs. I'd say the Flex is still in the easily-portable realm for most people, but 70lbs is in another league, and/or may require a 2nd person to help move. And having the flexibility of 2 batteries let's you only carry what you need. The Flex, even with the 2nd battery is also smaller. Also - see the note on panels above.
Warranty: Inergy is offering a 10-year "no BS full replacement" warranty (at least on presale) for the battery and 2 months on the whole unit. Titan only offers 24 months.
Cost:
Yes, the inverter is 1500w (Flex) vs 3,000 (Titan) - no getting around that. But if you don't need that power, and prefer the flexibility and size/weight of the Flex - here's a more accurate comparison:
- Titan (3kw inverter, 2kwh battery = $2995
- Flex + 2nd battery (1.5kw interver, 2.1kwh battery = $2200
Or - you can buy TWO Flex's for less cost (and combined weight!) of one Titan - $2700. That gives you a backup, or the ability to operate 2 sites, or the flexibility to stack batteries on one unit, and still have 3kw of power (though not on the same circuit obviously). For my purposes - that's great - I sometimes need that much power but I can split the load across different circuits. These are HUGE upsides for me.
I do have a DIY 3kw rig I build that is comparable to the Titan (for a lot less money!) -3,000w pure sine wave inverter, 24v LifeP04 batteries (210ah, expandable with a 2nd battery bank to 420ah), 40a of MPPT etc. But more often than not, I still use my Kodiak. Why? Because I don't always need that much power, and I can toss the Inergy over my shoulder (yes, it has a shoulder strap!) with a single 100w panel and just go.