Great question - I can't say there have been cases where businesses have implemented and not found it successful (though I'm sure there will inevitably be some). However, we do talk with businesses who are hesitant or just not ready for it.

Here's an albeit lengthy post I just posted on Twitter to a somewhat similar question for how we're looking to address that :)

Today, jumping straight to bitcoin is too big of a leap for the vast majority of businesses - I can give the best sales pitch in the world of why they should integrate bitcoin rewards (new customer acquisition, etc.), but they'll inevitably ask "well what about my existing customer base?" -- the answer of course is that maybe 10-20% of them would opt-in. At that point the business says well why bother.

So they need a way to increase that %. One way to do this is with branded (fungible) loyalty tokens that look and feel much more like a normal loyalty point to consumers (plus no business wants to willingly sacrifice the branding attached to their loyalty program). You can still back those assets with BTC, but it's packaged in a more accessible-looking vessel. Another thing you could do is back it with stablecoins instead of BTC - I know that sounds cringe to us, but now you've really removed every objection a business might have. If many businesses do this, it also gives consumers the ability to much more easily exchange these different forms of value vs. what they have today. And of course they can always convert into sats, and at least you've gotten people onto the network from which they can easily do that.