The ending is interesting, because Krell is an example of what the clones think the Jedi are during Order 66, and you're watching it play out with the roles almost reversed
Ever since I watched this arc as a kid, it has remained my favorite arc as well! Rex’s conversation with Fives at the end of Krell’s Carnage has always stuck with me dealing with the question that soldiers in war often have to face - if they are numbers on a chessboard, what happens to them when the game is over?
9:16 to play devils advocate umbarans are not soldiers. They will fight dirty and use any and every means to their advantage. And if they need to dressing up in clone armor to give them those seconds of advantage they would do so.
Hmm... true, but in that case, I would've liked a scene where it actually shows the Umbaran fighters dressing up as clones. At least then it would've given Krell's warning more weight...