[b]We are not going to use a system for this roleplay, as I did not advertise it.[/b] 

But, I think it's an interesting topic, because there is such a strong divide between people who like it and those who do not, so hearing people's thoughts are on the matter is always educational. I developed a casual system for a Magic: The Gathering roleplay, way back, that I based the first version of The Spirits Within's combat system on. The gist of the system was for it to be a decent bridge between text-based roleplay and tabletop, very streamlined and non-intrusive.

For example, there were a set number of 'character actions' for all characters, which were issued with 'action points.'This was just an anti-godmodding feature, that is, to prevent someone from killing everything in one post. One of the actions was "attack," which did a static amount of 'physical damage,' but the point was to roleplay it as several attacks back and forth between you and your enemy, block and misses, acrobatic moves, whatever—just as you would describe it in text-based combat, but you would be able to back all of your writing up with numbers in the background.

Then there was a static 'health pool' to indicate when and where a character would die. This part of text-based roleplaying is impossible to determine without ambiguity. I urged people to interpret different health values according to their own character, so what 20 health meant to character A did not have to mean the same to character B. it all depends on gender, body type, and those other obscure text-based things.

However, as Everblight said, the problem with this would be the extent of difference in magical abilities. But, I already stated that 'very specific' magical effects would not be very useful in combat situations. And 'status effects' such as being confused or whatever is easy to implement mechanics for. However, my biggest problem with the system, or any system, is that it becomes boring after a while unless you have a considerable amount of character customization in the form of traits, items, and whatever else, which was a nightmare to create and sucked the meaning out of 'simplicity.' 

So, I never used the system.