Let’s be clear, in my own mind as much as in anybody else’s, Santocure TBSI is N-t-butyl-2-benzothiazole sulfenimide, not to be confused, as it sometimes is, with N-t-butyl-2-benzothiazole sulfenamide (TBBS). It was introduced to give curing characteristics sulfenamides could not easily provide, namely a long scorch time and relatively slow rate of cure, coupled with improved reversion resistance. Hence, its suitability for thick components.
Perhaps the nearest sulfenamide contender is the dicyclohexyl derivative, DCBS, but this is very slow curing and not very efficient in terms of crosslink density. Replacing TBSI by CBS, TBBS or MBS (assuming nitrosamines is not a problem) ought to be possible with the aid of a retarder, but maybe not PVI because this does not reduce cure rate. A more conventional retarder such as salicylic acid may be more suitable. However, no advice can really be given unless more information on the rest of the formulation, the intended application and key vulcanizate properties is provided. For instance, is the vulcanizing system a conventional high sulfur one or is it a semi EV?
I am not aware of any other commercially available sulfenimdes.