This is a touchy subject for some in here, as 'The Longest-running Thread in Blatchat History' will confirm, but to answer your question "for a 1.8K is it worth doing?", I would answer yes, especially if you spend a lot of time in stationary/slow moving traffic (cities, M25, or sprint paddocks etc), as the lack of system pressure is kinder on head gaskets and plastic-cased radiators. It is also a 'fit for life' product, so does not require changing every two years like conventional products. Unless of course you start to notice a lack of performance, eg, your engine starts to runner hotter or something. FWIW; I've been using the Evans stuff for 3 or 4 years now, in a 1.6K which is mainly used for sprints and hillclimbs, along with public road blats around the Lakes. I think it is fine, but it's your choice.