I know of a company that works more like extending your engineering team, it's called Nearsoft, they have presence in the valley so if you live around I can drop you the contact info of one of the founders and help schedule a coffee meeting or something informal just to get to know how they work.
I recommend you them because they have several startups as their clients, some small other big so they could probably be a good fit.
I'll keep it there as this is starting to sound like an advert, so I'll leave my email: [email protected]
Sounds like a case where you would usually push through by yourself, but given what happened last time I think you would be better getting some extra help and getting the product out sooner.
I know a couple of outsourcing companies so I can give you a few pointers, good companies have NDAs and other contracts in place to protect you and your IP, usually they have US presence and they have workers on aligned timezones. I can say such companies are not rock bottom cheap but the quality and security it comes with them might be worth every penny (while also being cheaper than getting a full US team).
If you like I can pass you a few contacts in case you'll like to go this path.
This "good for X, it should be good for me" is something that bothers me, take php for example, if it is good enough for Facebook it should also be good enough for everybody, doesn't it?, sure, Facebook makes it work for them, but they spent a lot of resources to get there (they even made their own vm HipHop), that does not mean your startup has or want to spend that kind of effort and resources with it having now potentially better alternatives under your given use case?
I recommend you them because they have several startups as their clients, some small other big so they could probably be a good fit.
I'll keep it there as this is starting to sound like an advert, so I'll leave my email: [email protected]
Cheers.