Purchased the I5-4200U 16gb model to set up a few Hyper-V instances.  Was plugged in and ready to go in a couple of minutes, and Windows was activated without any issues.  The PC is small, fast and silent, and hardly generates any heat, despite being powered on for the last two days.Have since created multiple Hyper-V instances using various operating systems, and installed packages such as SQL Server 2019 running with 8GB with no loss of stability on the host machine, which had approx. 3.9gb left when running the Hyper-V instance.  The RAM and mSata card can both be upgraded, and 2.5" SSD's can also be added.The only negative point for me was the DDR3 RAM as this seems costly to upgrade, but there are several other models that use DDR4, so five stars out of five for me, and I would recommend this for anyone looking to replace an I5 desktop with a smaller unit while retaining the same performance.