Also rocking the PD-5610s on my Tarmac. Never had a problem with them, they work beautifully. The *only* (and minor) downside for me is that I have yet to find a LBS that carries cleat covers to make it easier to walk with the cleats on. And when I found some cleat covers for SPD-SLs online, they cost as much as the cleats themselves, hah. However I've gotten used to it and I am not walking far (within a bike shop / cafe), so it's no real biggie for me.