Hi Chris. I've never used this stuff, so I might not be much help. But, if it's similar to other liquid masking agents, such as Humbrol 'Maskol', there shouldn't be a major problem, especially if the paint is enamel. In the case of 'Maskol', which is a liquid rubber-like material, I normally very carefully lift an edge with the tip of my scalpel, and then just peel it off. If this is not possible for whatever reason, then using tape would seem a reasonable solution. However, if there is any possibilty of damaging the paintwork, due to it being concentrated around the mask, or in a joint for instance, then i think tape could be more risky than the scalpel,as there would be a larger area of contact. i think a tiny scratch from the blade tip would be easier to repair than a larger area lifted by tape. this would be more relevant still with acrylic paints.
It might be worthwhile duplicating the situation, by painting the same colour etc onto a piece of scrap plastic, or an old model, masking it and letting it set for some time, and then experimenting with removal.