Great question, I would love to hear feedback too. This year, mine are all getting at least trimmed because I am redoing my flower beds and splitting some of my bigger clumps.
In the past, I have done both. Never paid attention to how they ultimately did. Keeping some dead foliage at least at helped me identify where my clumps are while doing spring cleanup..... Because no matter how much fall cleanup I do, I still end up with tons of leaves to remove in the spring!
