No worries - I understand it is difficult to make any real pronouncements on what changes may come down the line from Eon - having the potential for a retrospective change landing on an end user is probably too big of a risk to take I suspect. It is conceivable that a person could export an amount of energy equating to over £1000 annually (split between green and brown electricity), to have that retrospectively apportioned and claimed back by a change in energy company policy would be a big stress hanging over the whole process.
Ref the 15KW TIC limit, I agree nobody "needs" more than 15KW, but I know of a few people who have more solar panels installed than that - usually because they have big energy requirements - EVs (though these might not be too relevant to solar), electric showers, maybe even the occasional hot tub etc, and beyond that I'm sure there are some that just get as much solar as they can to increase export potential, and then there are some who just want to be as green as possible and maximise their solar just for the eco credentials. I personally am way under the 15KW TIC limit, but having discussed with others I know some people who would like to use the next drive tariff but can't do so because of the limit, so I was curious if there was any overarching logic behind the limit that you knew of.
As mentioned above, EVs and solar are an interesting one - when my family were deciding to make the switch to EV, we decided to fully commit - getting solar, batteries and an EV all at the same time seemed to be the way to do it. However, we soon realised that solar / batteries were fairly irrelevant to the EV proposition, because using solar energy to charge an EV almost never makes sense - vehicles are generally most active when the sun is up, and each KWH of energy in the day can be exported for about twice as much as you can import energy in the night, when it is easier to have a stationary vehicle and schedule regular charging. Other than people with solar on the FIT scheme, I don't think I know of anyone who uses solar to charge an EV.