Hi! I have just enabled tiers for my Patreon site. Note that there is absolutely no difference between the 3 tiers or between choosing a tier-less custom pledge.
My reasoning is that currently about 2/3 of my Patreons pledge 1€ or less. The assumption here is that this is not mainly a lack of perceived value of my content, but rather simply the fact that Patreon sets "1" of whatever your local currency as the default. Don't misunderstand me here, I'm absolutely fine with you pledging 1€, it's still worth 100x more than a "Like" or just downloading without any comment at all. However, I want that to be your conscious choice, you should pledge what my content is worth to you, not just because its the default or simply not knowing that you can enter any amount.
Another point to consider is pledge efficiency. Currently AU$1 (or 0.65€) is the smallest possible pledge amount. An issue with these small pledges is that for European creators there is a flat 0.15€ plus 5% payment fee on every transaction below 3€. Plus 2.5% for currency conversion to Euro. Which means of those 0.65€ there are 0,20€ (or 30%) just going straight to PayPal or whatever payment provider you use. For a AU$2 (or 1,30€) pledge, it would be only 0,24€ (or 19%) payment fee, so you see that slightly larger pledges are way more efficient. Of course on top there is the fee for Patreon itself as well as income tax, but those are percentages that are independent of your personal pledge amount.
Again, there is no difference between the tiers, just pick what you think it is worth to you. That is surely different for everyone. If you are already one of my Patreon's there is nothing you need to do to continue having access to content.
Cheers, MacGruber