When a data source is "grayed out", it means that there is not an existing association between the primary data source and the grayed out data source. 

Not all data sources have associations to all data sources. By introducing this restriction, we are taking the complexity of understanding data joins out of the report building process for our customers. We'll build up more associations over time, and someday, customers will have the option for more control over joins in custom reporting. Until then, the availability of data sources serves as a guide to what associations are available for a given report. 

It depends:

• Does your customer use Tableau, Looker, or another BI tool to bring their HubSpot platform data into one place? Are the only reporting tools they use HubSpot, excel, and the BI tool? Then yes, they could evaluate the HubSpot custom report builder as a replacement. 
• Does your customer have a data warehouse? Did they hire a full-time data analyst or data person? Do they need full control over data joins and/or prefer to write SQL to configure data tables? Then no, this builder should most likely not replace their BI tool, BUT it could be a fantastic supplement to provide internal teams with reports in the place they already work, and is still worth evaluating for this purpose.

The new report builder does not have any special limits applied. Customers can create as many reports with this builder as their tier limit allows. 

Pro: 100 custom reports
Ent: 500 custom reports
Reporting add-on: 3000 custom reports

You can go to the custom report builder to create a custom report. All of these reports can be drilled down into, exported, and added onto any dashboard.

In the new custom report builder, we aim to let users report on many objects without having them wrestle with the complexity of writing SQL.

The user selects:

• The primary object
• Which associated objects to use

We automatically determine:

• How to relate the selected associated objects
• Which join type to use (always left)

Here’s a simple explanation of how it currently works:

In HubSpot, objects relate to one another in many different ways. A deal can be associated with a contact, or a company, or even both. The SQL-powered advanced builder automatically decides how to relate the objects you have selected for your report.

First, the builder attempts to join your associated objects directly to your selected primary object. Sometimes, however, no direct association exists. Therefore, the builder might have to find alternate paths, perhaps by introducing new objects into your report. For example, though products and contacts are not directly related -- deals may bridge that gap. When finding alternate paths, the builder tries to choose the path with the fewest number of steps between each selected associated object to the primary. The builder also prefers to use the most popular HubSpot objects, such as contacts, companies and deals, when selecting a path.