[Innomare]

There seem to be two different meanings for building "on spec".
Contrary to Lars, I believe it means "on specification". Which means that it is a one-off, built entirely on the clients' demands. These are usually written in a specification, which is the guideline for the design and the construction of the yacht. So actually almost the opposite of "on speculation".

I also believe that the way Feadship and Amels are going with their semi-custom designs (F45 e.g.) is not the right way. I don't see a real price reduction, so the only advantage to the client is the shorter waiting time, but that will be annihilated by the general increase in demand. Soon you'll be on a 3 year waiting list for a semi-custom as well.
Apart from that, I think Feadship and Amels are doing harm to their brands by offering "production boats". (let's face it, all production boats over 100 foot are actually semi-customs)
If I could afford a mega-yacht, I would cough up the extra percent or two-three it takes to have truly unique yacht. A client's input in a yacht is so much more than just the interior design (range, speed, sea-keeping, exterior styling, general arrangement, ...). And the concept design (if done well) is definitely the most enjoyable part in the construction process for an owner.
If I wouldn't want the three to four years waiting, I'd find a unique pre-owned yacht (maybe a designer yacht?) from the aft sections in the magazines and refit it to my preference.

Bruno