By the way, SMTP and IMAP folks, you're way ahead of the game. Your stuff is already reached the point of sublime unusability past which no fully compliant implementation is possible. Well done!
I'm a believer in "try before you buy" even if it's not something the vendor normally offers. Actually, if they don't offer some form of teaser or sample that generally makes me suspicious.
My personal requirement for sampling, with permission or without, is balanced with a requirement that I've had since I first began to make a living writing software, "If I use a product for longer than it would take me to earn to buy it then I am obligated to buy it." I can't reasonably expect people to pay me for my work if I refuse to return the favour for other's work. This means I buy virtually everything I actually use.
You will have many recoverable tape errors.