Hi Kitebug,
I am in a similar position to pneucube in regards to time spent kiting and I had my lessons with Red Baron as well. Having said that some of the best information I have received has come from speaking to other kiters and reading through forums to get helpful hints.
The hardest part at this stage is not knowing a lot about the sport which makes it difficult to choose what kite to buy. Essentialy if you were to test a kit you wouldn't know what felt right and what didn't.
The most important thing I feel when buying your first kite is safety. These days all kites have good safety release systems but anything 2007 or less you start to get a bit sketchy.
I will try and give you the pros and cons to both sides of your question based on my limited knowledge.
Red Baron + OnboardRed baron are great and if you have a chat with Guy he may be able to organise your first lesson in a group of 2 or 3 for maybe a possible discount - it might not be huge but it's worth a try :)
One thing I would be asking elements is if they have a helmet speaker system or something similar because with red baron I found it very helpful that they can talk to you via walkie talkie as you are flying down wind so you are getting as much info as possible while you face plant.
Onboard have both new and used gear so I would be asking whether the discount applies to new gear only. The benefit of buying from onboard is that they will look after you well if you buy from them in regards to any future repairs or warranty issues.
Onboard sell cabrinha kites which is what i personally use and out of the 8 people I have met out at parham 6 of them either currently have cabrinha kites or learnt on them originally.
What cabrinha kites offer is stability and predictability. They are very easy to relaunch and literally sit on the waters edge as you pick the sand out of your face when you complete your first superman in style.
The other advantage to them is that there are a lot of people who use them which means a lot of people are upgrading all the time which results in several second hand kites for sale that have only seen one season.
Elements + $180 refundFirst thing to think about is that generally a new kite can range anywhere from $1500-$2500 so $180 discount is essentially the middle ground here if you were thinking of a 10% discount. So depending on whether you buy new/secondhand from onboard and if the discount applies to both options the total outcome of the two schools ends up being the same.
Liquid Force kites have mixed reviews and if you search the forums you will see why. Having said that there are a lot of responses that suggest that the kites are good for learners and are value for money so really I beleive that you should head down to largs bay on a windy day and count the amount of liquid force kites you can see to help make your choice. I was down at the state freestyles this year and I think I saw 3 liquid force kites and a billion cabrinhas (rough estimate

). Not a professional judgement but something to think about.
One way I like to compare the two is to look at the iphone 4 and perhaps the latest Nokia or samsung - all the phones have fantastic features and you will always get fans of each brand but at the end of the day every man and his dog has an iphone which means every man and his dog will sell iphone accessories and everyone has created millions of apps and online support for the iphone. Question is do you want to be a pioneering wolf or another sheep :)
Having said that I would happily state that north, cabrinha, slingshot, naish are all proven brands but that does not mean that they won't have issues in the future if you buy second hand. I have had to repair a pully, leader lines, leading edge and bladder on my kite but that is after punishing it severly while learning.
So the real answer to all of this is how much cash have you got - If your loaded up I would go with Red baron and then head down to your local beach and start talking brands before heading to onboard to look at their range.
If your budgeting then be prepared to be shocked as you will likely end up spending at least $1200 to get setup second hand with some good buys so if you can get a good package with liquid force for a new kite and board then I can't see a negative side to this purchase as your first kite.
Hopefully this info helps. Fell free to PM me if you have any questions
Cheers :)