compare to Li-ion's 400-1200 This may be true for some kinds of li-ion batteries, but they can be engineered to last much longer than that. Tesla's daily cycle

compare to Li-ion's 400-1200 This may be true for some kinds of li-ion batteries, but they can be engineered to last much longer than that. Tesla's daily cycle home battery is warrantied for 5,000 cycles, for example. Assuming the battery doesn't die the day the warranty expires, this should give you at least 15 years of life. Not quite the 20 to 30 you're quoting, but current prices are much cheaper (and this seems likely to remain true, as vanadium in inherently expensive, and li-ion batteries have a head start in economies of scale). With massively reduced size and weight, shipping and installation should be much lower as well, and I suspect consumer uptake will likely be much higher for the foreseeable future.