There is a reason MBAs are taught market analysis. Its important to position your product for maximum effect (usually maximum profit, but that may not be the case here)
The arguments for FirefoxOS seem to be
1. It's OSS 2. It's Web-technologies only 3. It's aimed at the "emerging" markets' mobile users 4. It runs on cheaper hardware better than the competition
1 and 2 are great. And no-one but us cares, except in 20 years when no child has even seen a line of code because OSS gets wiped out as all PCs are replaced by mobile devices.
(This is the reason I want this to succeed, and I want laptops to be certified FreeBSD compliant. It matters!)
Anyway this is about market positioning, not OSS. So.
Its a well-known truism that don't be in the middle of any market - you get squeezed from both ends.
The emerging markets have adapted enormously well to only having SMS and no smartphones (see anyone in Mumbai). That is not going to go away, so the true bottom end of the market is SMS capable devices. They will probably just give them away.
If Firefox OS says we are not as good as iOS then thay are squarely putting themselves in the middle of the market.
Aim higher folks. The world is not segmented into feature phones and smartphones. It is segmented into one market "I want to use a networked mobile app to get laid or get cash." You will never be the bottom end - that belongs to sending cash by SMS, or selling your harvest with a text.
So its the top of the market - what the cool kids have.
And so, 1 & 2 might just be our saviours. Apple made a great new product that was catnip to the coolest kids in the West. Firefox OS is geeky cool - it might just appeal to the coolest kids not in the West. And they will want to buy the 'best' phone - aim high folks.
I hope you succeed.