I'm not running silverstripe with that high user amout, but am also interested in performance reports.

Is it possible to use one machine for 200+ Pages (simple templates) with about 1500+ DataObjecs and 10 concurrent backend users while serving (avg) 3000 hits a Day. Any hardware recommendations for this setup?

To answer the original question

Can Silverstripe handle a 10,000+ user database? does anyone use Silverstripe with a large amount of users? how does it hold up?

Yes if given the correct setup (hardware etc). I've used sites with ~40,000 member databases and performance (searching etc) is reasonable. Just don't use DataObject::get('Member'); (or any dataobject set stuff with large datasets). You are better off using SQL queries directly to sort, get data.

are there any metrics for silverstripes performance for this and any other areas the volumes can spiral upwards?

I remember there was a series of tables released for the 2.4.0 release to show the performance gains 2.4.0 achieved on data sets up to 100,000 objects but can't seem to track it down.