you bring up a great question regarding replacements..
on one hand, I really really wish all the muppeteers could be around forever, but, realistically, I know, and we've experienced reality and the changes that that sometimes forces on us, planned and unplanned. Several great performers have passed away suddenly, or chosen to step down due to age, illness, or desire for change.
While I haven't always agreed with Disney's practices in the past (still don't) I can completely understand a desire on their part to have well prepared and trained understudies available to fill in or take over the lead roles as needed.
This sort of thing was done with Frank/Eric and the change over went much more smoothly then did Jim/Steve and the parceling out of other departed performers where characters wound up being shelved for months or years while they waited for someone who could fill the role.
I am willing to accept this as a very real policy on the part of Disney. They would want the understudies to get some on screen practise and experience from time to time, and I can see that happening with some of the lower key, low priority outings, late night talk show pop in spots, or the mtv award bit (i didn't see that, but I somehow doubt that Kermit was really the intended focus of the bit..didn't see the other bit either.) But anyway the outings that would be expected to get lower ratings from their main target market. I would fully expect, however, that the main performer would do all the "big" appearances (unless there was a real reason he needed to be elsewhere..)
Would i want there to be 3, 5, 20 understudies? no, never. Do i fear that Disney would go that way anyway? yes, very much I do. quality would go way down and I would be extremely sad that my children and grandchildren would have to settle for less then I was able to enjoy.
so I would be torn, I can totally understand the need and desire to have well trained understudies available, but I fear they are willing to drop quality for quantity..
and as for our intrepid understudy. I haven't seen either of your performances so can not comment on quality, but will say that I'm sure that you did the best you could at the time and that your performances will improve over time and none of the comments made here should be seen as personal attacks. We were very unsure and critical about Steve when he took over, and there were plenty of comments made about Eric when he first showed up as well. While we all hope to have many many years left with Steve, if, for some reason, you are going to be taking over, even part time or just for a little while depending on what is going on.. we will probably eventually like your performances too... A good deal of the angst comes from the shock and the suddeness and the deathly seal of silence that seems to surround the whole deal..