Hiya Hennis,
100 watts is at the very upper end of what can be used to suit engraving. It will mean that at the tubes lowest strike power (roughly 10%) you may well be pumping more watts than you want to. 80 watts seems to be the upper end for line engraving (as well as being a MUCH cheaper tube replacement) as well as not really being (for practical purpose) that much slower than a 100.
80 to 150 is a big jump and 100 to 240 is a big jump but the benefits of a 100 over an 80 aren't really there to be honest.
20K USD? seems very high? I'm not familiar with the machine you write about but there are a large number of direct import machines from people like G.Weike that can beat that by 50% on price. A good point about the GCC machine is they use GSI tubes...(I just googled their site) now that's worth money (GSI supply some of the best DC tubes in the world) but in reality is the extra cost of that really justified in a new business (a GSI will die just as quickly if you forget to turn the water on).
I'd be more inclined to go with a Chinese import as a test bed for your business and then maybe look at a more expensive machine if the cost can be justified.
best wishes
Dave