I’ve been considering it, but not done so far. The device manager says its SATA so not NVMe. Albeit being SATA in the M.2 form factor. It appears the maximum upgrade currently is 2TB in this form factor, which would be a nice size for the i35. But it does cost almost 40-50% of the full cost of the machine itself. 🙂
Of course if you do decide to upgrade it. Make sure you clone the new drive in full including the hidden partitions containing the OS provided by the i35. I’ve managed to extract those hidden partitions to put separately onto a thumb drive in case of a catastrophic drive failure. In theory this should allow me to recover the i35 setup and OS to a new drive. But I would probably recommend cloning wherever possible as it’s a faster and more efficient way to upgrade the SSD drive.