Let me try to show it to you mathematically. I'm using 3 assumptions here, but I think you will agree that both assumptions are extremely reasonable and necessary.
1. Assumption: magic damage classes have to have similar output to melee damage classes. If either magic DPS or melee DPS was inherently better than the other we'd have major balance issues beyond RDM to deal with.
2. Assumption: RDM cannot be better at magic damage than a full caster or better at melee damage than a full meleer. A black magic double casting RDM cannot be strong than a BLM.
3. Assumption: RDM's total contribution to the party has to be similar to that of any other party member. So for example, whether he does it through black magic, melee, or half and half, his damage output has to be equal to that of any of dpser.[/quote]
I agree with all three assumptions.
The problem with a meleecasting RDM is that he can't melee and cast at the same time.
I think you missed the part where I said that "Meleecast" could be an RDM ability that allows them to melee and cast at the same time. As in, they do not have to stop meleeing in order to cast
Thus if an RDM was to melee at about half the strength of a melee, and cast at about half the strength of a black mage, (or maybe 40:60 or 60:40) and the RDM was doing both simultaneously, they would be doing half magic damage, half melee damage, and be equal to the melee damage dealers and magic damage dealers.
Using the numbers from your example...
Black Mage = 20 damage ice spell every 2 seconds
Knight = 10 damage melee every 1 second
A Damage Dealer is being expected to output 10DPS
Red Mage = 10 damage ice spells
Red Mage = 5 damage melee every 1 seconds
Double Casting Ice = The Red Mage would put out 20 ice damage every 2 seconds. AKA 10DPS
Meleecasting = Red Mage would be doing 5 melee DPS every 1 second AND 10 ice damage every 2 seconds simultaneously. AKA 5 melee DPS and 5 ice DPS which totals 10DPS.
Though like I said in my last post, it occurs to me that if meleecasting was used as a mechanic, that doublecasting would probably be redundant. It seems like you would either want the Red Mage to be able to "Double Cast White and Black Magic, but not be viable in melee" or you would want the Red Mage to be able to "Melee and cast spells at the same time, choosing spells to either backup-heal, or produce normal DPS, but not both at the same time."
Most likely, the superior option would come down to whether you view Red Mages as a class that should be capable of melee.
Now I don't think this necessarily has to be paired with the 'Doublecast' trait to work.
Actually, you accidently brought up another point that I hadn't thought of before. If both Doublecast, and my suggested Meleecast was two traits contained in the same class, it would be broken and literally mathematically impossible to balance without one being overpowered and the other being overpowered. The only way it could be balanced, would be if there was some way to force Red Mages to wear exactly 50% Strength and 50% Magic (Not really an option).
A RDM class that was balanced with both Doublecast and Meleecast, like mentioned before... who geared specifically for magic (AKA 40Strength : 60Magic instead of 50Strength : 50Melee) would be overpowered as a Doublecaster. Doing 120% of the damage they were supposed to be capable of doing.
Meaning that it really does have to be either Doublecast or Meleecast. Do they produce all their damage from casting (0Strength : 100Magic)? Or do they produce half their damage from casting, and half from meleeing (And thus go 50Strength : 50Magic, or 40:60 or 60:40, without changing their damage output significantly)
It would be truly impossible to balance if they have both options.
NOTE: I'd slightly lean towards Doublecast as the preferred way, mostly because the spell is canonically a Red Mage ability. However, I know a lot of RDM feel that melee should be a capability of RDM... so I don't really know. Edited, Jun 14th 2009 6:49pm by Karelyn