The quality of the leather depends on who installed it. Aftermarket leather is definitely not from the same source/supplier as the Toyota factory leather. If your car had the leather installed from GST with option code L2 then the leather is softer and had liquicell added which IMO makes for a more comfortable seat than the Toyota factory leather. If your leather was dealer installed then that would depend on what leather source the dealer used, there are literally dozens of different leather sources. Some very good and better than factory leather, and some not so good and inferior to factory leather. GST uses an excellent quality leather. If you are unsure whether the leather on your Prius is GST or dealer look on your car's window sticker and if it lists a L2 option for $1399.00 it is GST leather with liquicell. If you don't have the window sticker, PM me the VIN on your car and I can tell you whether GST installed or the your dealer.
My sticker in fact does list it as a L2...sounds like good news! Thank you for the extensive knowledge. Makes me wonder about some other items such as the color keyed side moldings (coded SM). To be honest...I did not even know they were on the car when I bought it (was not a key component of the purchase). But I have had a couple of folks ask about them on here...so now I notice them on a side note...sorry to hijack the OP!