Worth going from Cubase 7.5 to 10.5?

I’m currently using 7.5 Pro. I like it for the most part, and does what I need it to do. But I’m curious about upgrading to 10.5 Pro. But it’s a $300 upgrade for me, and I’m wondering if the cost is justified for the new features it provides? I’m not against updating at some point in the future, but I’m wondering if I should maybe wait until 11 or so. That money could be spent right now on some good plugins, etc.

I tried to find feature comparisons between 7.5 and 10.5 online, but couldn’t find any. Any thoughts if this is a massive upgrade?

Yes, stop wasting time. Lots to speed you up in 10.5

That means you probably are still using 32 bit plugins. That will be a big change, probably some work to go through them and make sure every plugin is on latest version because there as cubase versions go forward they require also having latest plugins (in a few cases) all-in-all it will run stable after all is done.
Keep both versions your system, don’t delete 7 because you will want to keep it in case issues with plugin and loading projects, at least until you are happy. I still have 3 cubase versions on my system.
Also, if you really need a few 32 bit plugins that don’t have 64 bits, I and many people use jbridge (small investement cost) but runs old plugins great.

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%.

Good to know this info. Also, does the summer sale happen every year in July?

It has been for a few years at least, as I remember it. You can never be fully sure though, it may change.