Hello Seahound,
Always consider very carefully any advise posted here by a manufacture or retailer. This is not say they are incorrect in their advice nor deceitful, just biased toward what they make and sell. In fact, if they did not show a bias toward their product(s) it would be a sad commentary on it's value. Check an individuals profile (mine included) as part of your consideration in accepting anyone's advice. Also, it is worth knowing that some of us who have been around a while also have bias toward the gear we use; this stands to reason, that is why we use it.
Now, to your question: An International Vagabond needs a regulator brand that has a good track record for keeping parts available for each model. Of course unless you intend to DIY, you also want a regulator that can be serviced by your local dive shop and at lots of locations in the world. The two best companies in both regards are Aqualung and Scubapro.
My recommendation for the average recreational diver, i.e. not freezing water, 150 feet or less, is a simple non balanced piston 1st stage such as the Scuba Pro MK 2 (or Aqualung Calypso, Mares R2, Sherwood Brut and a few others.) This simple design is usually inexpensive, nearly bullet proof, easy to get parts for and easy and inexpensive to service. It is also easy to DIY because it requires only a few o-rings and a seat. Yes, the unbalanced design will increase the breathing effort at low tank pressure, but I view this as a good thing.
For a second stage I like an adjustable and balanced unit. This provides the ability to have the regulator tuned to minimum inhalation resistance with the option of the diver increasing the resistance it if he/she finds the need. It is easy to see how an unbalanced piston first stage and a balanced adjustable second stage compliment each other well.
Hope this helps. Let us know what you decided and why.
c