Warlord was working on a new version but the pandemic put that on hold. The current version is still available.
Coincidently as 9th ed was being Launched, Warlord started doing a few articles of how to get into GoA, presumably trying to mop up 40k players who finally had enough of yet another edition and new army books etc being launched. So you could have a read of that and see if it sounds like your sort of game and I'm sure there must be a fair number of youtube games to assess GoA.
Mantic I've no idea about how there game plays but again there should be some youtube vids around to help.
Problem seems to be one of choice in finding a platoon to company level or reinforced platoon sized science fiction wargame in the 25mm or bigger scale.
There's some who have made attempts to convert WW2 games for 40K:
https://adventuresinscifi.blogspot.com/2019/12/40k-variant-for-chain-of-command.htmlAssuming your really want to stay with 40K however:
One of the reasons there may seem to have been more dice rolling is as I understand it burst templates have been replaced with that. I've not seen or played the newer editions but other than army being larger can't see there would be masses more dice rolling than you had in 3rd. I've also not seen the vid you mentioned.
As concerns the IGOUGO there is a pretty reasonable attempt to adapt to a bolt action activation for 8th, 9th being close enough it should work.
https://www.dakkadakka.com/dakkaforum/posts/list/741174.pageAs another option pick an older edition of 40k to play with your gaming group, if you liked 3rd then 5th is generally considered the best as it was wiith the same designers by and large. 6th and 7th had new team and it kinda floundered with those until 8th and a new direction.
There's a lot of love on the internet for 2nd ed and a few fb groups with files and a squat codex for instance and an activation system based off bolt action. So there has been some development on the game over the last 30 years.
Rules wise with any current edition with 40k is also the fact there will be updates and nerfing you'll need to keep up with.
Hope it helps with your choice, I think its a pretty reasonable move to play out the starter missions and see how it feels.
Happy Gaming.