As a small business, it is in our nature to partner and support other small businesses. After all, we are both in the same boat, understand the challenges, and are flexible with a "gung ho" attitude.
So we've done this a couple of times. The first business went into liquidation. The second lost 50% of its staff in one week (there was a single resignation from a two man band).
No matter the promises and the commitment, small businesses often don't have the resources to ride through a crisis (manpower, cash flow).
If you can, use the small guy to assist with New Product Development, but don't risk your whole business supporting them.
This is also why big businesses don't often use small businesses. The risk of non-delivery (or delays) is too high.