From what I've read--merely a rumor as I gather they won't confirm it, understandably--MBV uses mostly Flavor West as their concentrate source. The difference may lie there. MBV also offers up to 5 flavor shots, which is 40% flavoring by volume. I consider that way too much. But you've also got to remember that they've been around a while, and may be catering to a customer segment using less powerful equipment and wanting more flavoring even if it only helps in perception.
If you like MBV, maybe try some FW flavorings. Try a single flavor like Cinnamon Bun (or whatever you like), and mix several small batches at different ratios (10%, 15% and 20% for example). Can you taste them? Try again a week later, then two weeks later. You should be able to decide if you've found the right supplier, and get an idea of the amount needed for your taste. Taste is an area where "one size" definitely won't fit all.