There is no reason not to try it. But check the system carefully for oil leaks as you might kill the compressor. I would use some 134 with leak stop and a dye marker to make it easier to spot you leaks.
I've had much better experience. I used stop leak successfully on my somewhat older Ford vehicles to seal minor leaks. It stopped the leak, and I never needed to add freon again. Had no hardening or other issues. In fact, I gave my 91 Taurus to the nephew 5+ yrs ago and his family is still driving it....and the AC works.
Just want to add, the 91 used R12. I added R138 stop-leak to my 98 Windstar with the same positive results.
Consider putting in a can each year of the regular stuff.
$6-10 a year.
You might see oil where it is leaking out, and decide if you want to fix it and go through the evacuation and filling process.
R134a with stop leak? They promise it is safe for the system, and it probably is, if you only use one can one time.