あしたの歌 in my ass

With 4x 2TB SSDs we’re already at 480€

Not sure that would fit in the budget

Xbian uses upstart

Go with Mint, it’s my daily drive on both my laptop and HTPC. If you choose the regular edition Ubuntu based you have also hardware enablement (hwe) kernels which could be useful on newer hardware.

“How’s the catgirls thing going?”

Clonezilla can also update grub. Last time I upgraded system drive I had to do nothing.

HP Zbook 15" G7 working out of the box but not great detection reliability (might be an unfortunate specimen). Lenovo Thinkpad T580 much better although not working out of the box on LMDE

You can try with libreelec https://forum.libreelec.tv/thread/13250-testing-8-9-004-x86-acer-aspire-one/