upgrade a 2011 HNAS 3080G2?

I know what the correct answer to this challenge is.

No, I should not attempt to upgrade an 8 yr old HNAS 3080 G2 that's completely out of support...

but if someone here has done this and found it to be completely painless and easy, I'd consider it anyway.

It's currently on 12.4.3924.15 and I'm trying to get it up to 12.7.4221.12 for improved SMB2/3 support.

Looks like it's attached to their unified storage HUS130 platform, which is also 4 yrs behind on firmware updates.

Any of you guys gone through this?  opinions on difficulty?  likelihood of it going terribly wrong?

Can you rate it on the Isilon scale of frustration? 

10 - hardest = pre-emc purchase, I swear this had data on it 15 minutes ago...

5 - medium = post-Dell purchase, upgrades get stuck half way through, your firmware update has not been fully applied puzzles

1 - easiest = 7.X.X.X in the sweet spot of EMC ownership when it all just worked right

I appreciate any stories or anecdotes you guys have to offer as I've never touched this platform.