Tamiya is a huge company with a well established distributer network and brand presence in the market. To pick up on your point Dan, they don't need to shift a lot of their big box tanks - the big box is there to scream "We are Tamiya, we are bigger and better than anyone else" down from its perch on the top shelf, just the same as their 1/350 scale Battleships and Aircraft Carrier models do (How many 1/350 scale Nimitz's do you reckon they shift per year, and where do their owners store them...!? [X(] ). The motor industry calls that a 'Halo Model', think Dodge Viper or Audi RS8 here - both cost a ton of money to develop and go racing with, and neither of them is going to contribute much to the bottom lines of their respective companies in unit sales...

Heng Long on the other hand are in the business of selling cheap toys by the container load. By starting out with essentially a dumbed down, knock off of a Tamiya Tiger that retailed for around $50, they were able to (relatively cheaply) bring out something that looked 'OK' to the casual buyer when viewed on a website such as ebay, and could be bundled with a load of other r/c toys as a single shipment to the retailer. By starting out at the low end they managed to grow up to where they are today and still (presumably) command the same margins for a much better product.

Compared with this, its hardly surprising that Mato and Hooben aren't shifting much product. The Sherman is more expensive than a HL for those who are just looking for a toy, and the guys looking for a large scale kit to build are going to spring for the Tamiya because they have the brand recognition. (You can probably also argue that Heng Long have a degree of brand recognition these days, as a google search will likely bring up more positive posts than negative ones...). I heard recently that WSN have quit making their T34 and Tiger, I would have to assume these same reasons played a part in that decision.

I wish Hooben and Mato the best of luck, but they have a mountain to climb to get to the point where they can command the sales needed to justify further products - until they start reaching people outside of the (globally tiny) R/C Tank community, they aren't going to be successful. It really doesn't matter what they sell, if few people have heard of them or know enough about them to consider them against the alternatives.