I probably wouldn’t use the word expert to describe my experience, but I have used the velcro setup a few times and can share my experiences.
I have not had issues with any corrosion on the guns I have used the velcro on. Bath have factory finishes.
You can remove the velcro if you decide you don’t like it. It can take some effort though. Not sure what it would do to a cerekote finish. I don’t have much experience with cerekote at all, so not sure how that might go.
Match the size of the strip of velcro to the cards you plan on using. Be sure to accommodate any pins in the receiver that might need to be removed for maintenance. Clean the surface of the receiver really well (I use alcohol). Apply velcro like a decal you want to be really straight. I usually put some weight on top of the velcro for 10-15 minutes after applied. Not sure if it actually helps though.
Good luck.