i have previously owned the High Standard derringers in 22 LR and in 22 magnum.
I carried them on the weak-hand side.....and with the thought in mind that they were for absolute last ditch "get off me now" emergency usage.......not as a backup to the primary should it go down......and never as the primary carry.by itself...it was for a very specific up close and personal, about to die, Hail Mary role for the weak hand only..
the design is small, flat, and snag free. No safety to manipulate, no hammer to cock.....making it less fumble-prone for potential dexterity problems with the weak hand under hasty conditions......like rolling on the ground or flat on your back..
for the above job description, i can honestly not think of a better, more capable, jam-free, small handgun design for the weak hand unsupported.........think of it like a knife......i can appreciate the High Standard as i have no knife skills, but i can pull a trigger with my weak hand..
it is also obsolete......on the rare chance parts are required......good luck finding them and someone willing to work on it......you probably can, but it will cost you money and aggravation.
Barrel regulation affecting poa/poi will do more to limit effective range than the caliber/power......my experience is that this is a .seven yard "hit the b-27 somewhere" type gun under speed......be much closer if you want to keep the shots in the eight ring of that b27.
you can find data on the 22 magnum as far as capabilities, gel testing and such...and come to your own conclusion. I think the 22 magnum is fine as a last ditch "get off me now" caliber that is suitable for this derringer format.....heck, it was made for it and used in said backup roles as last ditch by officers...
if you just want a derringer because it is a "derringer"....and want an excuse to buy one.......go for it, just know and accept the limitations. It is a fun minimalist piece to work with and has history as a good dao design..
if you do not need the above job description of a weak hand only last ditch gun and you are not sold on the derringer concept......then there are much better options out there in caliber, accuracy, and capacity........the kel-tec p32 comes to mind as i believe they have improved the magazine.. 380's are in abundance.....and even the 22 LR is coming on strong in auto pocket pistols.
i honestly can not see myself paying 300....but you might want it more than i......