Okay, let's ignore arithmetics and just allow comparison. As you've said, a common practice is to normalize it into some standard notation with a well-founded ordering. But there is no mechanical way to convert (or even bound) a computational representation to such notation---the general approach is therefore to compute a difference and check its sign. Not really good when it can continue even after the heat death of universe...
Frankly speaking, I rather expected to see some improvement over Level-Index number systems [1], but it turns out that this post is completely unrelated to number formats. Otherwise it is good, hence my mild frustration here :S