I know this question is old, but I use both XtraReports and SQL Reporting Services in the project I'm working on, so maybe some contrast may still help someone.
Xtra reports are very similar to Crystal - they use stripes. It’s very quick and easy to compile a report with a header, detail and footer. Groups easily retain their capabilities, and DevEx processes information about which fields are collections and can be turned into detailed reports. Also, the "Calculated Fields" provided by Xtra are useful for reusing the same custom formulas.
Reporting Services provides more flexibility by implementing tables and matrices instead of using ranges. Actually, getting the finished report out of this takes a little more time, and getting exactly what you want, with attached reports and detailed reports, takes a little more time and practice, but in the end you have more flexibility to do things that aren't built by Xtra because, like running reports side by side on one page or organizing a report in any way you want, instead of being limited to horizontal stripes. Another minute for Reporting Services is that it does not have the Calculated Field support that Xtra does, which means that at any time you have your own formula or expression that you want to use more than once when you need to copy and paste it into each individual field. SSRS is also good with built-in fields such as runtime, page numbers, etc. While in Xtra you need to do something to find these global variables.
In conclusion, I would go with SSRS in the long run, because it provides much more flexibility. The management system is great for creating related reports, also if you want to save different reports with different parameters.
Hope this helps someone. Good luck