Yes, that’s a massive 6 versions update and totally worth it.
Here are some of the features added from 8.0 to 10.5:
Render-in-place, chord pads, plugin manager, performance boost, VCA faders, Lower zone/window handling, sampler track, mixer history/undo, Frequency EQ plugin + a bunch of other plugins, more marker tracks, Automation bézier curves, better metronome, more insert slots, direct offline processing, Halion Sonic SE 3 update, adapt to zoom, automation range tool, VariAudio 3, audio alignment, revised channel strip, Groove Agent SE 4+5 update, Mix console snapshots, ARA, AAF, video follows edit mode, easy side-chaining, Latency monitor, colorized mixer channels, Import Tracks from Projects, combined select tools, retrospective midi record.
And a lot of other things too.
You can see some more things if you scroll down on this Wikipedia page (it shows additional features for each version):
About Cubase 10 here: http://admiralbumblebee.com/music/2018/11/14/Cubase-10-update.html
Yes, that’s a MASSIVE update.
There use to be a summer sale for udates in July I think, so if you wait just a couple of weeks you may possibly save 40%.