The other thread didn't get bogged down, it ran out of steam. Since you wanted to pep the topic up I don't see why you couldn't have posted to the existing thread but it's not my call.
Anyway, just a quick comment or two on your alternate methods and their disadvantages.
1. Direct conversion
Disadvantages:
Impossible. There is no direct corellation between WH and TW stats, they are different games with different game mechanics.
However, you can approximate many stats by looking at the reasoning behind them and coming up with a reasonable conversion formula, as or similar to what I already suggested in the pre-existing thread.
2. The converstion equivalent of twinned towns
Disadvantages:
Working with subjective relationships is inefficient. Imagine writing all these subjective, non-formulaic conversions down as a reference material and you'll get the idea. They would need to be referred to or the risk is losing your place or train of thought during such a long process, not to mention coming back to it at a later date for additions or corrections.
It's definately inaccurate if you want to include other than human units. What does an orc compare to, or a dwarf? How about something way on out there as far as M2TW is concerned, like a rat ogre? You could get creative but why hammer square pegs into round holes if you don't have to?
Bookmarks