In reply to Nick.

First, I want to apologize and say that I didn't intend to sound rude or insult you in anyway. Truly.

Your take is very interesting and well thought out, I just completely disagree. I've been working in the e-commerce side of WordPress for 5+ years, on a very successful project with a very large user base, I never once heard/seen an attack on their site as a result of the e-commerce plugin they had installed. Nor was the plugin exploited. Under those conditions you would expect someone to target these sites regularly, since the content was much more valuable to an attacker than a client list (that Sprout Invoices creates).

As you can tell I've done this for years; while a WP site could be exploited because of a core security issue it's not fair to impose the security risk on any plugins or themes (unless the attack vector was created by the plugin/theme).

I consider the majority of the "sensitive" data stored on a site using Sprout Invoices has the same value as the form data stored with estimate/lead form submissions; people trust form plugins to store submissions so I see very little difference with Sprout Invoices. The payment data stored is useless since API tokens can't be used by any other person, since they're tied to the API credentials and the site owner.

That said...
I'm sorry you w/couldn't trust any Sprout Apps with any business process for you site. I think you're missing out (especially with other plugins, e.g. contact form plugins) but it's a matter of choice and it's yours to make.

Thanks for the feedback.