The reputation hit for blocking on the web is more or less permanent for most companies. Sure if I'm running Opera, I'll probably switch browsers to access Google. But Paydirt ain't free, it ain't Google, and I don't think I need it very badly.
What I'll have to say about it probably won't be positive.
What you have to say about it probably won't be positive if you use Internet Explorer and it doesn't work. No loss to Paydirt! In fact, a gain - they don't have to spend any development or support time explaining why they don't support the Internet Explorer specific bug you encountered.
IMO, when it comes to accounting software, the browser shouldn't make a damn bit of difference to how it works, only to how it appears.
If a choice of browsers breaks a modern accounting application, that's poor design, not a feature because an accounting app damn sure better not be relying on javascript's math capability.
What I'll have to say about it probably won't be positive.