Just ordered an RC-4 from kniveshipfree.com
My bet on what Ontario is sending RC is a "demand" or "threat" letter.
I am a lawyer, and have always found it curious that RC was going to be designing and selling "product improved" versions of the Ontario RAT line.
There might be something wrong with that even if your design ownership is as free and clear as you believe it to be. That's because irrespective of design ownership, Ontario might try to make the case that the RC line is a "trade dress" issue, and there being a RAT-3, RC-3, RAT-4, RC-4, RAT 6, RC-6, so on and so forth, confuses the buying public and harms Ontario's sales via a cannibalization effect.
Frankly, I think that effect is overblown. I already own all of the Ontario RATs I was ever going to buy and now I am intent on acquiring RCs.
However, I might yet sell off my Ontarios on the secondary market, having more adequate RC replacements except for in the case of my RAT-5. Those second hand sales might hurt Ontario's bottom line by preempting a first line sale to a new buyer.
I'll bet that they want a name change and cease and desist from confusing the market place as their opening gambit.
You can probably thump them on contractual grounds if your contract was as stated. That said, they'd be foolish if that were the only claim they brought.
97+% of all cases settle at some point. There's no need to freak out yet. They are going to demand more than they ever expect to get, and if your contract is clear, you'll have counterclaims of your own to pursue if they sue.
If they do sue you, I think I'll take a torch my RAT 6 and twist it a few times, after writing "SCREW YOU!" on the scales with a Sharpie and send it on in telling them to keep it.
I never bought an Ontario before the RAT designs and if they sue, I'll be damned if I ever buy another.