Originally Posted by veganbikes

Do you need it, no until you need it, then you NEED IT. It is a product designed to break, that is its goal because if it breaks it will hopefully save your frame typically a more expensive piece so having a spare for touring is probably not a bad idea. Wouldn't want to get caught out at a bike shop that doesn't carry that part and then having to wait to order it. You can get an emergency version as dsbrantjr suggested but like it says it is an emergency to limp you back home to a shop in an emergency it won't get the full gear range and may not always work on all set ups. However like he said I would just have the correct one for your bikes. It will weigh about the same and could save your behind.

I think if your bike has a replaceable derailleur hanger you should own a spare for it. Wheels MFG makes a good lion share of them and they are of good quality and made right here in 'Murica. The new SRAM unit is for frames designed for it, they want a new standard to rule them all just like all the other standards that exist to rule them all. Not a bad idea but one that keeps popping its head all over bikes. Somethings have stuck and not been changed a bunch and have a bunch of different options like bottle cage and 3 pack mounts, they all seem to be the same size these days so it is something that is actually somewhat universal (at least as far as I have seen) and not needing of other crap.