I want to post an enumerated list. Instead of 1), 2), 3) as you did, I write 102), 101), 100), 99). Nobody bats an eye because these numbers are very useful.
RR looks like this to me:
1, 2, 3, 4, 5, 6, 7, 8, 9 ... 99, with the lowest number meaning "lems come out slowly" and the highest number meaning "lems come out quickly." This makes sense, works as I need it to in-game, and no further information is required.
SI, on the other hand, looks like this:
107, 106, 105, 104 ... 4, with the highest number meaning "lems come out slowly" and the lowest number meaning "lems come out quickly." OK so far, I guess, but now I need more information ... why is the lowest number 4? Why does it stop at 4 and not go all the way to 1? Why does it
start at 107? These are questions that, as a player, I am bound to ask whether I've seen a Lemmings game before or not.
So, maybe I take the time to find out that it's the number of pixels between lemmings. OK, I understand it a bit more now but... is the game really going to expect me to know about pixel distance between lemmings? As a casual player, that's a bit of a red flag!
1 - 99 is intuitive and simple; I can see that, when the number is higher, the lems come out faster. A scale going from 107 - 4 makes
far less intuitive sense to me personally, even when I know what it means. I don't care about the exact pixel distance between the lems, I only care how it translates to what's actually happening on screen, and I can find out by playing the game what sort of figures are useful.
New keyboards will be produced. Instead of the "1" key, they have a "102" key. If we don't want the two extra digits when we type, we can erase them afterwards every time. I'll buy this keyboard, I think that keyboard is as useful as the ones we have. 102 is a natural figure to type often; after all, most people start counting from here.
Heh, good way of illustrating your point

But, I don't actually agree that RR presents this sort of problem. "Low is slow, high is fast" is all the player needs to know, and wherever exact figures come into play, "RR75" means just as much as "SI28" if what you're seeing on screen is the same result.
you make a symbol for fast and a symbol for slow, then you don't have to swap them
Yes, great idea. UP and DOWN arrows could work, or maybe a single right-facing arrow for "slow" and 3 stacked right-facing arrows for "fast"; I'll see about making a split button with the number displayed in the centre. That way, continuing to support both RR and SI should be easy enough even without graphic-swapping. That solves the third issue.
If the votes remain as they are, I'll likely keep the option and not try to crowbar it into Classic Mode. That way, I can forget about it, those who want to use it can do so, and the Config menu is kept relatively clean and tidy.