By who?
Done it to your bike?
It's highly unlikely that the product that at the centre of this thread is any different to the tens of nano-coat products that have been on the market for many years. The differences in these products essentially come down to the amount and type of silica that's added to the product and which vary the product in terms of its 'harshness' protection and it's water dynamics properties. On the latter, the silica addition is either designed to be either hydro-phobic (270 degrees) or hydro-phillic (90 degrees), the former designed for body panels and the latter for wheels (to sheet or use water flow to wash brake dust away).
The amount of silica makes the product either harder or easier to apply (easier it is, the more you can avoid streaking as the product cures at a slow rate, i.e. more than a minute or so). It's also the case that silica compounds designed to provide a harshness layer will often not provide the water-repellent properties, hence kits will often come with a silica compound for the harshness layer, to be topped with a water-repellent compound.
Gyeon is acknowledged by the detaining fraternity, professional and amateur, to have some excellent products (not just ceramics), but are the many others such as gtechniq and carpro.
Most kits, depending on their mix, will cost around £50 to £90. Other than the properties you are choosing of the products what matters more is how they are applied, in terms of preparation of the surface, coverage, application (avoiding streaking vs ineffective application), and whether radiation heat was applied (if required).
£320 for a day's labour plus products seems fair to me. New car detailing will usually take two days (including a first stage polish) and cost around £550-600.
Guarantees usually require that the vehicle is returned for a maintenance cost of the top product. My experience is that whatever claims are made for products you can usually reduce that by 40-50%.
There are top-up sealant products you can use (e.g. Gyeon Cure) but my experience is that it won't prevent a natural degradation in the ceramic coat over time and that the best you can expect of even a professionally applied product is 30 months' observed effectiveness (i.e. beading).
For me, the use of ceramics on motorbikes is just an additional tool of protection. Unlike a car, there are just so many irregular surfaces and nooks and crannies that you can't cover, so ultimately your best protection is the regular use of acf50. And whilst I would pay to have a new car professionally protected, I wouldn't do so for a bike.
However, as I'm comfortable with using the products, I applied gtechniq crystal serum (harshness layer) and two coats of exov4 (repellency) to my TB, though confess it was done in the middle of winter, and so there were only so many surfaces I was going to fret over.
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