I have been using Checkfront for a few months. Still struggling to get it to do everything that I would like but have found their support to be quite responsive for helping to customise. I am in the middle of a Groupon campaign at the moment. Found it really simple to integrate the vouchers but it is far from perfect in Checkfront from a booking perspective. For us (and it may be different for the way you have it set up), you can either set it to a 100% of value or a specific $. The issue for us is with multiple price points (eg. adult or student), we can't use a fixed $ value so have to use the 100% of value - however, when people make a booking they can actually select multiple stations for 1 voucher and it will accept that. With Groupon, it doesn't make too much of a difference though as that just makes the booking for the session and we have to scan the vouchers when they come in store anyway (and it is clear that one voucher is for 1x1hr session on the ad). Hope that helps....
