In fact, I may try this. I too have heard that a mouse pad has a bit too much give and can wrap around and blunt the apex.
I think this is true for those that have a heavier hand, like I do.
So - here is what I think about convex sharpening:
First - to clarify terms (for the terms of this discussion):
a) Convex Grind and Edge - Where the convex grind goes all the way to the edge (apex).
b) Micro Bevel Edge - An initial grind (of whatever type) with a secondary bevel at the edge.
C) Full Convex - A grind from the spine down to the edge.
D) Sabre - A grind from a little below the spine down to the edge.
E) Scandivex - A hybrid type grind where a person puts a scandi style grind on a knife but instead of using a traditional V grind - they use a convex edge.
With all of this done - Andy, on his convex knives, generally does a full or sabre grind and finishes it with a secondary micro bevel.
Some people keep this initial secondary bevel and thus can use something like a sharpmaker, a set of crock sticks, a simple sharpening stone, or something alone those lines. Essentially they are treating this knife like the grind on your average pocket knife and only sharpening the secondary bevel.
With this said - many people find that simply sharpening of the secondary bevel, over time, gets them to a secondary micro bevel that is too steep - and thus now and again will take a little off the primary convex grind.
Personally - the first thing that I do is to use Japanese water stones (or in a low grit sandpaper) and grind the initial bevel all the way to the edge (making the Convex grind and edge all one grind). I then take this one grind up to 4000 grit (on Japanese water stones or about 2000 grit on Wet Dry sandpaper) and then take the whole thing to a JRE 4 sided strop bat. I polish the entire grind down to the edge being careful not to push too hard at the edge (this will cause the substrate to give too much and cause the very edge to become more obtuse).
I use this method for all Convex grinds.
For True Scandi Grinds (like that on my Arete) I use Japanese water stones (that have been freshly lapped) and bring the edge to 4000 grit and the strop lightly as mentioned above. Yes - yes - this puts a slight convex microbevel on the edge of a scandi. I am sure my stones were not PERFECTLY flat to begin with so I suppose this would be a convex grind to some people. Blah Blah Blah. This is at a much more micro level than my unaided eyes are capable of taking in and so I don't worry about it.
The point, as I see it - is to bring whatever edge you have (Micro bevel - full convex - scandivex - Scandi - etc...) to the most true edge you can (the right side meeting the left side at the same point all the way down the edge - and the angle you desire) bringing it to the highest polish and most true edge that you can. The rest is a matter of preference in grinds and angles (essentially geometry).
That is my two pennies on the topic.
TF