Where/how may I get information/instruction about this subject? How do Keiko Abe, Gordon Stout, L.H. Stevens play?
Is this roll possible with Burton grip? (as opposed to 4/3 - 2/1) - but retaining the advantage of using #1 and #3 mallets for playing lines.

Keiko Abe plays, I believe with a Burton (cross) grip. From what I understand, she often will play independent rolls as just fast double verticals, but I do not know about her ripple roll technique. Stout plays with Musser grip (if I recall correctly- I can verify with some of his students if need be), and Stevens, obviously plays with Stevens grip. The way that I was taught to develop the ripple roll with Stevens technique was to play a sort of flam from 4 to 3, then a flam from 1 to 2- playing the grace and primary notes at the same volume. As you train your muscles to make that motion, you then train your mind to merge those motions by increasing tempo between the flams, until they are all equally spaced notes- a ripple roll. I'm certain I'm not the foremost authority on the matter, so if anyone else has any further insight, I'd love to learn more, as well. I hope I was able to help to some extent.

Any roll permutation is possible, regardless of which grip you use. Contrary to the dogmatic text, the principles of Stevens' Method of Movement apply to ALL the grips, not just Stevens.

LHS chooses to use more obvious (to the ear) roll permutations than the rest of your list.

WM

I've found it easier to perform a ripple roll with a Burton grip, perhaps because of the natural pivot created by the crossed mallets in the palm. It's also easier to bring out certain voices by having more "weight" behind those mallets.

With Stevens grip, I use a hybrid of a flam stroke ripple roll and Stevens' double lateral roll. With a flam stroke ripple roll, it is difficult to bring out the outer mallets as they naturally hang lower. With the double lateral roll, I tend to get a more staccato roll with each note emphasized. With my hybrid roll, I move the fulcrum point futher back into the hand, allowing for more movement with the mallets, the outer mallets moving in the same direction as my wrists and the inner mallets moving in the opposite directions.

With the ripple roll I find that I can play only up to about a forte level, with the ripple roll becoming ineffective at especially large intervals.

-Michael

I may be mistaken but I believe Musser ripple roll was actually more of a "flop" because the grip on the 2 outer mallets were loosened to hit the bars in a flam-like fashion. To develop a more diverse ripple roll to where you can use any sticking permutation (i.e. 1234, 4321, 1324, etc.) I suggest using exercises 279-294 in the Stevens book to develop that.
Hope this helps!

Ray