The following exceprt is found in the newly re-release eBook Introducing Windows Server 2012 (thanks once again Marnix for sharing useful content). I'm interested to see how ETW and similar enhancements in Windows Server 2012 enable performance or other improvements in System Center's infrastructure and application monitoring.
Performance Monitoring Improvements in Windows Server 2012
Windows Server 2012 exposes more Event Tracing for Windows (ETW) data providers and performance items than Windows Server 2008 R2. With this exposure comes the vital need for the IT professional to know which datasets are relevant to their specific monitoring situation. It's not feasible nor appropriate to just gather everything, for system monitoring has in it a touch of physics … a modified Heisenberg uncertainty principle is afoot; One cannot monitor a system without impacting it to some degree. To how much of a degree is at question. Finely tuned data collector sets by Performance Analysis of Logs (PAL; see http://pal.codeplex.com) can be used by the IT professional to ensure they are only gathering the data necessary to their problem set, so as to not negatively impact system performance too heavily while monitoring or baselining systems.
One advantage to using ETW data providers rather than performance counter object items is that ETW providers come from the kernel itself typically, rather than coming from user mode measurements. What this means is that the data from ETW data providers is more accurate and more reliable and also puts a lower load on the system. ETW logging is unlikely to suffer from missing data sets due to high system load as well. Look for guidance on which items to collect though before diving in; ETL tracing can grow log files quickly.