I believe in diversification in both taxes and investments.
About 7 years ago, as my portfolio was rapidly increasing in value due to large additions from a few good years at work (and some decent investment returns in the 2005-2007 era), I opted to put about $7k, split up among two different fraternal benefit societies that had 'decent' rates on their deferred, fixed rate annuity (similar to a CD, except non-qualified and not insured).
The rate has been ok (minimum of 3%, but had a 4% yield for a while), and it obviously isn't the main reason I can hope to retire early one day
....but, as a small way to diversify, it was ok, in a sense.
Depending on what your cash needs are, and what rate they're offering, it could make sense. Just make sure you fully understand what the interest rate forecast is, and if it's just a "forecast", or if that rate is exactly what you'll be getting. Also, understand that while it's not as risky as a junk bond, there are some limitations to the protection that an annuity offers in terms of "insurance". And, make sure you aren't agreeing to automatically turn it into an immediate annuity at some point down the road, instead of having the ability to withdraw from it penalty-free after 59 1/2.
10% of your entire portfolio sounds like a large amount - would it be split among different insurers? What is the max limit for the state insurance associations' coverage for your state of residence?
Personally, I'd be uncomfortable with that large of an amount with a single insurer - it would have to be high enough for me to consider it. Also, consider the insurer's financial ratings and outlook.