I agree on not using armor against lower equipped players. At the very least, taking half of ruby armor off is good enough IMO.
By my calculations a while ago, full Ruby Armor upgrade cost ~3000 gold without sale. Best farming method yields 1 gold per minute...even with a 60% sale,
1200 gold = 1200 minutes, or 20 hours in survival...
Thus, this game really isn't suited for new or casual players at all. Farming for 20 hours to get "broken" armor and join the RAP ranks is ridiculous.
It's probably more interesting (and tempting) if you spend the gold on a variety of equipment, rather then focus the bulk of it on armor.