Not sure if my connectors are worn down or out of spec, but noticed that different types of plugs can seemingly be connected together. Not sure if there will be any downsides to doing this in the long run? But on the AIO side, it seems the old GNB27 is the universal connector and will accept all batteries (BT2.0, A30, and GNB27). However on the battery side both the A30 and BT2.0 seems to plug into all FC plugs. 

I just saw reference to the A30-BT2 compatibility and a recommendation to build with A30 connectors for this reason. That being said I'm going with BT2 on all my 1S quads.

It seems if you go with BT2.0 or A30, both are cross compatible and possibly more battery options in BT2.0. Why did they recommend the A30 over the BT2.0?
However I do find it takes quite a bit more force to disconnect a BT2.0 connector, so you will need to take care especially if you're prone to pulling off battery leads.

It was from this build of a copy of the fractal

https://www.google.com/amp/s/nuxnik.com/...guide/amp/

I think the author claims it has the same cross compatibility but is also 'open source'. Not sure what that means in this context.

I find it hilarious that while trying to monopolize the lightweight battery connector market, they just ended up with a bunch of standards that generally work together without hassle. It's probably not a bad idea to grab BT2.0 plugs and get A30 batteries as they'll be cheaper without the proprietary BT2.0 connector on them, and you can get options that aren't BetaFPV. (I like BetaFPV alright, but options>brand loyalty.)

It sorta sucks that there's no A30/GNB27 cross compatibility. I'm pretty invested in GNB27. I converted my open prop 1S stuff when they first came out and it really woke them up. Chargers were lacking but I have tracked down a few 6-place options. It was a cost/availability thing for me. GNB27 packs with matching leads in the box were about the same price as others and readily available on amazon. It made it very easy to try out... That reminds me. I need to look for some more GNB27 power pigtails or connectors to make some more. I want to convert some whoops... I have a few dozen batteries right now but as they die off I don't know if I'll replace them. We'll see if the A30 has taken off by then or something else has become "the standard". FWIW, I never even considered BT2.0 due to price and availability.

I have no brand loyalty to BetaFPV, as they have royally screwed me over twice with badly designed product they put in print themselves as unusable as stated in their own sales blurb yet refused to support / help me out of the non-compatibility they had created.  That's not a forgive and forget matter!

I'm using A30, partly for that, partly as I tend to use GNB cells anyway.

A30 work smoothly, hold well, def help flight duration, and are cheap. Only thing to watch for is the GNB sold A30 variant is quite low temp melt plastic, so you must have the other half connected and be quick. Personally I wish they were NOT black as its harder to see which way round they are in some lighting.

@drumgod      -   I had just bought a pack of five male and five female GNB27's when A30 appeared, so they were not used.  I did offer them here a while back, to no takers. Postage probably makes it untenable if not in UK though. suppose it depends on how desperate you are...........  

Would be great if nbd nitro nectar or any other folded cell 1s could get these .. I know they have the BT2.0.. but like you said… price

@BadRaven: Thank you sir. Much appreciated but I'm sure you are correct; postage would be ridiculous. lol.