Some users of high end Lumia phones may be frustrated that the Windows 10 Technical Preview is not available on the Lumia 930, 1520, and Icon. Microsoft has released a blog post explaining the know issues within the Windows 10 Technical Preview and a brief section of it explains why some higher end phones aren’t receiving the preview.
Microsoft explains that while the OS takes up the same disk space as Windows 8.1 there are some partition related issues preventing the preview from being available. “We have a feature that will be coming soon called “partition stitching” which will allow us to adjust the OS partition dynamically to create room for the install process to be able to update the OS in-place. Until this comes in, we needed devices which were configured by mobile operators with sufficiently sized OS partitions to allow the in-place upgrade, and many of the bigger phones have very tight OS partitions.”