While trying to balance the relative merits of the speedstrip versus the speedloader, I'd think that practicing loading,
in general, probably needs more attention for a lot of revolver shooters who carry their 5-shot (or more) revolvers for dedicated defensive weapons.
I remember when we carried duty revolvers and there was a stage in the qual where we had to partially reload and fire 4 rounds at one point. I think it involved firing 10 rounds in 25 seconds from about 20 yards, and the time limit remained the same regardless of the method used for loading the last 4 rounds. Not exactly difficult for a competent revolver shooter, although trying to load loose rounds did make for a bit of a harder time for folks using belt loops.

(It also reinforced the shooter remembering which way their service revolver cylinder rotated, if they were loading less rounds than it took to fill a cylinder, as we had guys carrying both Colts and S&W's.

)
Bottom line?
Nowadays, I carry strips for convenience (flatter & easier to pocket), but I'll still occasionally carry speedloaders. Sometimes both, especially if I'm traveling. Why?
Simply because if I actually expect there's an increased potential risk of having to (re)load under stress, the speedloaders are
always going to be faster, letting you dump 5 rounds faster than it usually takes to load 2 charge holes. Insert, twist/push versus insert, peel & pull.
I'm disinclined to try juggling 2X2X1, or 2Xskip-a-spaceX2 and leave an
empty charge hole to index under the firing pin hole, under stress. Speedloaders are much faster and load
all chambers at once.
Now, since I'm retired from being fully active I no longer have to carry a 5-shot snub off-duty while thinking I might have to invoke my peace officer status and take an enforcement action. Trouble is going to have to work to find me, so I don't carry speedloaders all the time. Speedstrips are probably fine for my typical retirement needs. (I even started carrying them more often when pocketing an Airweight in dress slacks when i was attending conferences & seminars as both student & trainer toward the end of my career.)
If the circumstances of my daily activities or travel make me suspect I might really
need more than a 5-shot snub, I'd either change my planned activities ... or carry one of my pistols that have 6, 7, 8, 9, 10 or 12-rd magazines (which I sometimes do, anyway, depending).
When it comes right down to it, when I carried a 6-shot service revolver and a pair of speedloaders on-duty, I often carried the same setup off-duty. When I eventually adopted a 5-shot snub for off-duty, court appearances and attending other admin/training functions, I realized I was trading away that 1-extra shot inherent advantage in both the gun and the speedloaders, and I carried
speedloaders more than
speedstrips. The strips were for convenience, which could be argued to imply a certain amount of laziness regarding the bulk of what I was willing to carry in my pockets.
There's always some degree of compromise involved. Risk assessment and balanced compromise.
TANSTAAFL, folks.