My advancement through the fg farming went something like this:
use flay em for my first FG kill. Used it until i got money for 6 upped RoLs.Did grind AI3 for lobos (bronze arena nowadays offer better chances)
used Ro/hope whith 3 lobo for FG.
slowly upgrade the full Ro/hope
Worked out pretty well for me. I would not suggest anything else for FG farming grind wise. Since then tried most of the upped fg grinders and seem more or less Ro/hope equivalent, except instosis (dont fancy the pace of such decks personaly but very effective) and SPLAT (my personal top fg grinder, but requires shards)
Would recommend both of those decks but uprading flay'em does not seem to improve its chances... so go for upped Ro/hope. No real point in using Ro/hope with less than 3 lobos for serious grinding. Thats my 10 cents, hope it helps