To be honest a second or third rate bot will be able to make just as much money as Rebornbuddy -- not because Rebornbuddy lacks features but because the best way to get Gil from resources is via shard farming, which is probably SEs fault. But yes, Rebornbuddy can do it very well.
Why Shards are better than actual items:
They are always in demand, highest turnover rate items.
Reduces equipment durability extremely slowly -- less bot maintenance
Doesn't take up inventory space -- again, less maintenance
Higher level nodes give more than one shard per swing -- efficiency
You can even just do shards naked and save on the repair bill too because they have 100% gather chance.
When I used to bot shards on my server I used to make 720,000 a day running probably on average 15 hours a day. You can probably make as much in solid assets with Snurbles and Fleece, but I ended up having a Retainer with all 175 slots filled with Fleece/Snurbles because they just don't sell as fast. With shards you can just undercut the lowest seller by 1 and you would have sold it as soon as you send out your retainer.
I don't do that anymore since I only did it to make capital, now I monopolize consumable markets (Market PvP) and make about 5 times as much money -- if I can be assed to do it, considering it takes personal time which a bot can't do. On the other hand I don't worry about gil anymore since I have 400+mil on a non-legacy server.
Also, yes, varies wildly server by server.
Materia on mine is super cheap except for Det ones, so there isn;t any money to be made with Materia on mine. Maybe if you're on one of those servers with ridiculous Materia costs spriritbinding can be much more efficient. If you have a smartphone with LGE or HSPA+ I suiggest you grab teamViewer so you can see how your bot is doing and to unload your equipment, convert and equip new ones since RB has yet to have a Materia Convert feature.