Ease of entry is a bit of a BS argument for road. On road, you're stopped. When stopped, an SPD-SL pedal will naturally rotate with gravity to the same exact spot every time for an easy entry.
An SPD does not. An SPD shines in terms of shedding muck AND being able to clip in and out in dynamic (in motion) situations.
Even if you could run in a hypothetical SL cleat, and hypothetically it didn't take on muck......in a cross race on a dismount/remount you can't depend on gravity to return the pedal to a good entry point. Here, the SPD being dual sided wins out. Or 4-sided if you're an egg beaters rider.
Or in MTB if you're unclipping an inside leg during a slide in a corner or something.
I argue for a fitness oriented road rider to go with SL's simply for the ability to use the same shoe and same pedal on multiple type bikes and be able to comfortably walk anywhere you want to. And durability of a hidden metal cleat.
If I had to pick a commuter pedal/shoe, it would be a really comfy lace up and a combo flat/SPD setup where it's got the little cage around an SPD pedal.
Why SL's for road then? They're quite a bit lighter. Combined with a dedicated carbon road shoe I'd bet an SL setup could be a full pound lighter than an SPD shoe with sole and SPD metal pedals. Maybe not a pound, but it's a LOT.
That's my $0.02.