Rat Cutlery's owners, Jeff Randall and Mike Perrin designed the knives but didn't do the actual manufacturing of them. Ontario was contracted to do the manufacturing and they were branded as Ontario RAT knives with model names like the RAT-3, RAT-7, RTAK, RTAK II, etc. Long story short they parted ways due to differences in philosophy and Jeff and Mike then started working with Rowen Manufacturing and rebranded the updated designs, model names, as well as adding new models like the Izula and RC-5 as RAT Cutlery. The names changed to RC-3, RC-4, RC-5, etc (RC standing for RAT Cutlery).
Within the last year or so they've expanded on their product line, and continue to do so, adding fire starting kits, back packs, etc. As a result they've rebranded the company name to ESEE Knives. They've also been involved in jungle survival training for years and hold regular courses in the Peruvian jungles.
As far as quality goes, the new product is better made, better fit and finish, better heat treatment on the blade steel, better warranty (one of the best in the business), etc.
They're also great guys and regularly participate with forum members in their dedicated ESEE sub forum here on Blade Forums. Swing by sometime, it's a fun place to hang out. Just remember to leave any ego at the door!