So a mixed review (its a long one)
The short version is: the free plugin is great 5/5 - BUT I wouldn't recommend paying for the pro version 1/5, due to bugs, poor customer service and refusal of a refund.
The long version:
I started with the free version which was/is fantastic. However because we wanted a drop down menu in the checkout for selecting where the customer had heard about the event from - we decided to purchase the pro version. BIG mistake in my experience.
There were several bugs, including required fields still being required when unchecked, form data being stored so other visitors to the site could see the details of who last entered their personal info, poor spacing and formatting between the custom boxes.
Partly my fault - because I tried to make the purchase at the time we had a mailing campaign etc... live, so there were time restrictions and other factors for me to consider.
unfortunately upon purchase, and a panicked message from my client, (yes I did my own tests) - the bugs were discovered and several sales suspected to be lost. I contacted the plugin designer - as at that time the support forums / website for the plugin were down (think it is working now) so I couldn't create an account to search for help.
After a looong chain of emails, the designer was helpful in one way - helping getting the program installed and the activation key working (another problem despite me following installation instructions fully) the designer basically said that the fault is at my end, that I needed to make a test account to find out where the problem lay (I tried disabling all other plugins to fault find - didn't make a difference) - so support was offered, it simply wasn't up to standard or timely enough from my perspective.
So I had by this point resorted back to the free version, and asked for a refund as the hassle and time commitment needed to get the plugin running satisfactorily and without bugs (that were supposedly due to something at my end of things) was way too much for the small pay off, coupled with the intial delayed response of his support and the support website being down, and the sales that we suspect we have lost - makes me feel justified in asking for a refund. (and I mentioned that I would be willing to donate something for the free version as a goodwill gesture/thanks for such a great plugin - still "no" to a refund)
He has refused my request of a refund with the suggestion that I make a test account to trouble shoot - I am not willing to do this, as this process has already caused some degree of stress. $30 down the drain.
So to summarize - the free plugin is great 5/5 - BUT I wouldn't recommend paying for the pro version 1/5