I have to say C# is a massive improvement. Sure, I liked Monty/MABL's ease of use and quirks that allowed for out-of-the-box thinking and gimmicks a lot, but the same dependence on gimmicky workarounds limited it greatly (having to rely on parties or troop inventories to simulate arrays, no way to work with strings apart from joining them together and some other stuff that should have been trivial otherwise). Monty just can't handle such a supposedly ambitious game. It's not 2012 anymore.
Not to mention it allowed for a limited amount of scripts/tuples, making it harder to read and work with. With C#, you can create as many functions, classes or objects as you like, organizing your code better. It's also supported by a lot of common IDEs, which helps with debugging and reviewing.