I've been power trolling with DEs for a long time with only a couple minor issues, I would not consider anything else for muskie myself... but to each their own. When rail mounted, they have a fairly low profile and I've had no issues or complaints just leaving them in place while casting. I have had the DEs chew up the trigger of the reel seat, but never the cork, and you are basically a wing-nut spin away from removing them for casting, a quick pivot of the remaining base and it's nearly flush on the rail... that is if it really bothers you, or for longer term casting situations.
They are the most efficient rod holders for muskie by design, and you can quickly and easily remove a loaded rod from one of these holders once you get the hang of it. I have had a few people in the boat over the years who had a problem getting them out of the holder and then dropping them back in the pocket, so I understand what some of you are saying in that regard. However, for me it is just as important to be as proficient at maintaining and setting lines trolling, as it is with casting. More times than I can count, (or more accurately remember), I have cleaned a fouled bait, dropped it back out and almost instantly had a hit... every second counts. In short, DEs definitely help to keep my boat running optimally. Any more they are almost automatic for me, and I will occasionally do a one-handed lure check with a prop wash down rod by pivoting the DE on the rail while only holding the rod butt. I lift the rod with a snap to keep the DE open, then lift the bait to the surface, check the bait, and then drop it back in the open holder, a quick pivot, and the rod is back in the water at an almost 90° angle to the boat in 10 seconds. As mentioned (pictured) by Andrew, being able to easily pivot the DE to maximize the prop wash bite is what really separates them from all others IMHO. | 
