So, I have been looking over the rewards you get for trading in renown and trying to decide which ones would give the best ROI.
1 hour xp bonus (10%) - 10 renown
1 hour crit bonus (2%) - 10 renown
10,000 gold - 15 renown
6 lessons - 15 renown
30k gold cap increase - 20 renown
3 hour xp bonus (10%) - 25 renown
3 hour crit bonus (2%) - 25 renown
60 lessons - 140 renown
600 lessons - 1300 renown
an adventurer's giftbox* - 2000 renown
So, unless you are low 20s and 30s, I don't see the 10k gold being very useful and I don't know what the 30k gold cap increase is about at all. 6 lessons seems like a waste of renown regardless of what circle you are and so does 60 lessons. So that leaves the xp bonuses, crit bonuses, 600 lessons and giftbox.
Looking at the amounts required and the amount of renown gained per task depending on difficulty... you are looking at a minimum 70 days straight doing tasks on hard just to get the giftbox, assuming you complete each task since you can only take 1 task per in game month. So for the lower level, non-transed toons like myself... would you smarter and more experienced players recommend getting the xp and crit bonuses to increase leveling thus increasing gold production for credits, or is it still more beneficial to just do the highest difficulty you can for each task and just wait for the giftboxes?
If you are running just medium, you are looking at 100 days for a giftbox, vs 2.5 days for 3 hour crit or exp bonus.
Easy would be 200 days obviously. So over half a year for 1 artifact. Somehow that just doesn't seem like a very good ROI... but I could very well be wrong.