Actually it's a more general question about Human-Computer Interaction, where user is able to browse sequential options with only two buttons (up-down) and there are two indications of current state. One is a display, and the other is for example different sound (or a timbre) for different states. However, user can recognize the state by the sound, but of course this is much slower than visual recognition.
The discussion is what is more convenient indication (faster to operate with):
1. Index of the position in the list, i.e. two or three digit numbers
2. Name of the item on the position
At first sight when a customer is looking for a multi-effects pedal, he or she could be attracted by the wider displays of some of the pedals, which indicate names of the effects, but is it really more useful?
While I've been playing with a pedal with name indication for a while, it was surprisingly for me to realize, that numbers seem to be better in particular cases...
With a guitar multieffect processor, with name indication you've got a list of names:
And you see just one active at a time.
Imagine the list is 60 items long, and you need to switch between items which are on a 30-step distance and you don't know the exact distance.
You know the name of the target and you can recognize its tone, but usually you wouldn't remember how many times you should click on the pedal to get there. Probably you'll remember the names which are immediately around the target (due to the attention focus when you search for it and find it). However, generally you'll know just if they are "far" or "close", not exact numbers, and after all names suggest you not to count on numbers.
Unless you remember the whole list in-between - i.e. all names and their order - and unless you can imagine the distances between effects, you'll have to click the buttons or push the pedals slowly and you should be watching the indication.
On the other hand, if the indication is just two-digit number, you can easily remember both numbers and quickly pass through the others, without watching the steps in between...
Of course, number indication has it faults, too. First of all, they are less fancy... And they don't help you to create a named link between the sound and the effect (or say the state of the system). For example, it's good for a young player to know, that this sound is for Solo, this is usually Blues etc. (Even though he or she can recognize it by ear, but what ever... )
Also, names are useful for editing effects using software tools, for example Digitech RP150, RP250 and RP350 come with XEdit.
For education purposes, using name indication is better.
If you need to switch very quickly between given positions, without the burden of learning a new alphabet - go for numbers... ;-)
Don't be tricked to choose a pedal for its wider display! Choose it for its tone.