It won't hurt you to use the same summary as long as the Hub has plenty of original content, but in general it's best to link hubs together that are closely related by the topic and useful to the reader.
Linking tightly related Hubs together in the content of your Hubs might be a better way to go. You can do this in the text capsule. The words that you choose to link from one Hub to another is called anchor text. By using good keywords as your anchor text, this can be beneficial to ranking in search engines for the phrase used in the anchor text, as well as very helpful to your visitors if the links are useful.