After playing for a while I really started to like the plate covered. It can take many many hits and doesn't feel too slow.
The problem with slow (<85 speed) shields is that everyone just holds their attacks against shields now, while maneuvering, hoping you drop your block or let them behind you. The best counter against these holds is to feint dropping your block, i.e. press attack, but then quickly raise shield again before the strike lands.
With a slow shield, you can't recover fast enough to block the swing, so you either have wait forever hoping a teammate attacks the guy holding attacks on you, or attempt kicks, or chambers or other risky maneuver. 87 speed (like the +3 HRS I use), is not quite fast enough to reliably feint dropping your block, although it works fine against slower weapons. I used a 90 speed for a while (+3 brown kite), and it was usually fast enough except against longswords/etc.