Have you ever been to a site that has so much information you have no idea where to start? The homepage is so long you have to scroll and scroll to see everything. It’s so long and there is so much to look at that you have no idea how to find what you are looking for.
This is something that I see over and over with real estate sites. The problem is agents that have no idea about web visitor viewing habits are their own webmasters. If someone would tell them that a visitor will leave a site that looks complicated, even if the info is there, to find a simple and clean site with the info maybe site owners would do a better job of designing their sites.
You can have to much content, you can have to many options for navigation, you can cause yourself to loose visitors by making your site to complicated. Ask 20 people (friends, family, past clients…) that have never been to your site to look at your site and see how long it takes for them to find your MLS search. Anything over 3-4 seconds is way to long. Also ask them is your site makes them feel comfortable and if it’s easy to find things.
In the end you will have multiple peoples opinions and that should help as every site can improve. Plus you just exposed your site to 20 new people 
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Can you have too much content? No. I think you are blending two pieces of the puzzle. Design and content.
Can you have too much content on your site, I don’t think you can. I think the more you have the better.
However, I think you have to present it in a way that doesn’t overpower the reader and make them flip to a new site. As a former graphic designer, I printed out a saying and had it on the wall above my computer: “Remember, White Space is my Friend.”