My only problem with encoders is that you then rely on the fact that every one of your customers' hosts has installed the extension for the brand of encoder you buy. And you can be guaranteed that the list of brands is not getting shorter...
Personally, I prefer to use an extremely modified version of a PHP obfuscator that I made. It allows you to exclude obfuscation of particular files and particular function names, variable names, class names and constant names. That way I get to pick and choose what gets hidden (and I can use wildcards in my list, too).
I think I prefer just not to have the hassle of worrying about what's installed on some hocky 2c / decade hosting company in the middle of the jungle somewhere. Yeah, I don't automatically get licensing code with it, but I have my own obfuscated library that does that anyway...