Speed-Loaders are faster then Speed-Strips by a considerable margin.
But Speed-Strips are more compact for the amount of ammo carried if you carry CCW in tight clothes.
I like Speed-Strips a little better in J-Frame S&W's because there is hardly enough thumb latch clearance for Speed-Loaders to work.
I prefer Speed-Loaders for K, L, and N frame guns & exposed belt holster carry.
Optimally, you would have & practice with both, and use whichever is more appropriate for the occasion & dress.
If nothing else, they keep 5-6 rounds of ammo together in one place
But if you ever actually need to reload under fire after expending your five shots? Well, while you're fiddling around with your so-called speedstrip, the individual or individuals responsible for your current lack of ammo will have plenty of time to light a cigarette, amble on over to wherever it is you last fired a shot from, and park one in the back of your skull.
If the bad guy is that close, you should have a better plan than reloading....like attacking the attacker with another weapon or retreating until you have time to reload....distance equals safety....
Two speedstrips fit in an empty Altoids mint container. The Altoids container fits nicely in a shirt pocket.