These are perfect for 60-150A and briefly, 175A, which is a LOT of current flow. Advantages over EC5 and XT90 include . . .
- More compact
- More current
- More flexible
. . . and putting this into context, and in reverse order;
More flexible - you can use two of the same 6S packs for a 12S model just by making a serial connection. Doing the same with any block-type connector (EC5 or XT90, for example) requires buying a serial adapter.
In the real world, I use 6S5300 packs for my E-flight F-16 (80mm fan). And I use two of the same packs for my 12S-powered HSD Jets F-16 (105mm fan) because the (+) of one pack connects to (-) of the other. Electrically the two 6S are now a 12S pack. And because this leaves one (+) and one (-) for connecting to the ESC, there's no change in procedure. But the best part is no adapter means less voltage loss!
More current - I use the 5.5mm for everything from 60A to 150A. And they’ll briefly do 175A
loads. Meanwhile, EC5 are OK to 120A, and 100A for the XT90. So the 5.5mm handle more current than either.
More compact - block-type connectors are bulky compared to bullets due to a plastic housing. Ditching the housing saves weight and eliminating the bulk of the connector itself can be important for some models.
But the real benefit is more handling current, and making easy series connections. For example, if you have three 4S packs, connecting them in series again gives you a 12S pack electrically . . . no adapters required! And this is important when you fly models with 4S packs, and others with 8S. Ditto some with 6S and others with 12S because it reduces how many packs you need to buy, and manage.
And consider this final point, 6S chargers are dirt cheap. So having two el cheapo chargers versus a pricey single 12S capable charger. With individual chargers you not only save money vs the pricey 12S capable charger but in the event a charger craps out, because you have two, then while the rate at which you can charge is decreased by 50%, if you only have the one charger and it craps out, you're dead in the water. Win-win!