The stock CE armor in the arms and shoulder held up fine, I never hit my back but I replaced it with a KNOX dual density one just because the original is better used as a yoga mat than a back protector
Important point. An excellent instructor I had one time said that you can't live without a head or a spine. SAS-TECH might be even better than Knox. It is a high tech foam that is fairly soft with slowly compressed and is hard when rapidly compressed. The usual mail order outfits have these and others, and they can be trimmed with a knife to fit 'most any jacket. Under $50.