hello Nick, having the same model and year I went through all that palaver, too. Usually on the phone you say, yes, it has a factory-fitted SAIS immobiliser (which it does). Then, they pause, aand ask if its Suzuki type one or two. To which the only answer is 'Fecked if I know'. Nowhere that I found does it define it any more than that!
But the brochure for that year does say ''SAIS - Suzuki Advanced Immobiliser System - An electronic id system in the owners key to prevent unauthorised people from starting the engine''