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It depends how many services you offer. Right now you're listing 3 and that fits fine in your navigation, but at some point you may want to add more services. I think what you're doing now works, but I'd create a services menu if you have other services. We can only give you opinions on this forum, so you should test both and see what works better.

Domain and page authority are more a factor of the number & quality of links you have coming into your site, so shouldn't be affected by content changes. Many companies offer more than one distinct service, so it's common for homepages to offer users a choice of which service they are interested in and then provide a customized landing page for that segment. Here are a couple examples off the top of my head: http://37signals.com/ http://www.copyblogger.com/ http://www.clickbank.com/index.html http://www.express.com/home.jsp

Good luck!

That's even more useful.  Thanks for both the great resources.