What are the affects of changing the order of the levels within prosites on my existings signups?

I currently have 2 levels for my prosites setup:
Level 1 - Pro - £7.49
Level 2 - Blog - £2.49

I now want to add a 3rd level, eCommerce at £10.49
I want to re-order the levels so that when they are viewed on the checkout page the order is as follows:
1) Blog
2) Pro
3) eCommerce
i.e. ascending in price order.

I know I can drag and drop the order of the levels, my question is this - what affect would this have on my existing clients signed up to my network? I currently have around 30 people signed up to the Pro level, the blog and eCommerce levels have no one signed up.

Is it safe for me to go ahead and change the order, or do I need to consider what it will do to my current subscriptions?