Quote from the article: 'Most other forms of athletics (xc/international mountain running/track/road) use u9, u11, u13, u15, u17 categories, and use a reference date of midnight at the END of the year of the race. The age categories, in everything except what we call them, are identical'
For XC (and possibly the other forms mentioned) this is incorrect. Intercounties XC, Northerns, etc do use these age groups, but based on age on 1st September in the year prior to the race. So someone born on my birthday, 27th of September, is in one age group for XC and another for the FRA series.
More broadly, as a junior myself until last year, I believe that abolishing the u18 category (would be u19 under the new rules) would be unwise. The last 2 years I have raced in the u18 category and thought the mixture of some races being juniors only (e.g. Coiners) and some the u18s racing with the seniors (e.g. West Nab) provided a good introduction into senior fell running. Turnout may have been low, but the alternative seems to be a direct jump from the under 16 (to be u17) age group to the seniors. Personally I have enjoyed senior races as much, if not more than junior races, but I am not sure this would be a view shared by all juniors. Has there been (or is there planned) any consultation of those most affected by the changes - the runners themselves?
On another note, I have always thought the age groups being based on the start/end of the year to be slightly odd. I know one of the arguments for this is that it 'evens the playing field' for those born out side of Sep/Oct/Nov/Dec, but this results in the situation in which I find myself currently - in school year 13 but unable to take part in the junior series. Would it not make more sense next year to align the age groups fully with the XC schools age groups, introducing an u19 age category next year but for schools years 12 and 13, rather than on the basis of age at the end of the year?