So...

If you're only doing basic-level, not really. You need to get A-rank reward tier or better for a *chance* at the good stuff. The main 'good stuff' are:

• AP (it's bad at Basic, though)
• Alban Knights Emblem. Judging from the patch notes, they work like upgradeable totems, but you need a lot of runes just to make a complete one to synth into another. Do keep in mind they break if you fail trying to synth Level 4+ Emblems, though. The cap is level 5 for any one emblem type, far as I heard. I don't have enough runes to upgrade mine, so I can't really tell you if the stat benefits are worth it.
• Alternate source of Crusader EXP.
• The (very rare) coin drops in supply chests. I was lucky to bump into a chest that has a Gold Alban Knight Coin. It's worth 100k when NPC selling it (and it even allows you to deposit said gold directly to bank, due to absurd value, though you obviously get less due to bank deposit fee)

tl;dr version: generally nope, though opinions may vary if you can handle S-tier or Hard-rank stuff.

Due to the whole "3 times a day" restriction (and I can't run it more than once on my comp due to memory issues), this is going to be a huge pain to do research on.

In all honesty I don't think those gold Coins are rare, every single time I've ran into the Supply Room I've gotten one :/

I was only quoting directly from the main page's article on it. Running into the Supply Chest in and of itself is rare enough. Ignoring the lucky streaks, there isn't enough raw data to disprove the actual rarity of the gold/silver coins yet.