I would love to see patch even further, 4.9. Many people forgot that they've changed abyss, added garrisons, and mythical BM gear in the new base there. It was an amazing experience leveling your base, getting bonuses, etc. The same goes for sieges. They brought back and changed how sieges worked in the upper abyss.
Stigmas, yes. Personally, I love how they changed stigmas. First of all, they removed many many useless skills or merged their effects with other skills, making them more powerful. Cleric was especially buffed in that patch. Same for Templar, Gladiator, Ranger. Don't know about other classes because I haven't played them much post 4.8. Many stigmas were simply converted into normal skills. It is true that vision stigma is a pain to get, and that's something to consider.
PvE-wise there were many great additions and changes. Makarna, RST Heroic, Runa Heroic, Enhanced RST gear, enhanced Hyperion gear. More myth accessories from Runadium. Enhanced Sauro Accessories. Kaisinel's Daevanion gear. Oh, and let's not forget, the go-to instance of every bard - Rentus HM for that sweet attack speed harp. Also, Chaos rift for those who are hunting manastones. So yeah, there were many great things to farm for PVE players.
PvP-wise - Mythical abyss gear, Officer-2 Accessories, and wings. Despite many saying that Katalams were go-to PVP zones, Signia and Vengar were a lot of fun to PvP in. Runatorium was a great addition to PvP instance list with mythical PvP accessories and great looking skins.
It would be great to see this patch in a private server because it was released to close to 5.0, many people didn't bother with a lot of things because there was no point back then. If they were to released 4.9 now, it would take players a good amount of time to grind everything that it has to offer, which would increase player retention.