I noticed the supporter function the other day and signed up as coffee.
The pertinent feedback is that I'd begun to sign up as cake but was deterred from doing so by the mention of the possibility of an uncertain currency charge (I may have got the wording wrong, but I expect you'll know what I mean). I imagine you have good reasons for choosing a USD based system however expect that if I've hesitated, then others will. I'm not complaining, just trying to give helpful feedback. If it's possible, perhaps some indicative values of charges may help with confidence.
Once I have some knowledge about what charges paypal impose, I'll consider upgrading to my original intent.
Please do keep up the good work.