When I was out at Nationals, I tried asking how the Ontario system works (I mean the actual data entry, not the formula behind the system). Nobody was able to tell me.
In BC, we only use match results, and we just import the results into an application that parses the data, adds it to the database and generates updates automatically. I don't know if you have something similar in Ontario, or if someone enters the data manually.
In a perfect world, I still think that something in between the two systems would be ideal:
1. Classifier scores from matches could be added for classification data using HHF like the US system (not the ICS system). I really don't like how a bad score generated from something like a squib or a jam pulls down your results. I like the US system that ignores scores that are more than 5% below your current classification level. Not a perfect idea; someone has already pointed out that classifiers test fundamentals rather than match performance, but it does allow people to get classified if they don't travel to a tonne of level 2 or 3 matches. To minimize the effects of 8 stage "classifier matches", we could adopt a policy like the USPSA one. In USPSA, you actually can only include 1 classifier stage per match with the exception of a "classifier match" (4 classifiers maximum) which can only be held at the club once per year.
2. Level 2 and 3 matches could be submitted as Classifier scores, just like USPSA Area matches count towards classification. Recognizing that sometimes GM's are not in attendance, an application of a "correction" factor could be applied to classifier matches. (this is what we do in BC). If a Master is the highest ranked shooter in attendance, then the match winner is only awarded 94.99% (highest percent for M) and all shooters only receive 94.99% of what they actually shot. Still has some issue and flaws, but these could be minimized by combination with classifier stages.
3. I really hate the ICS rolling average; I like the BC system where you only go down after set, annual dates; you can only go down in class after the Provincials, but if your scores indicate you should go down, you can petition to stay in the higher class if you feel that your scores during the year were not reflective of your ability. However, it is the board's discretion as to whether the petition should be granted. If it was a Canada wide system, it would probably be easiest just to scrap the "petition" process as it's hard for a national system to make exceptions for people in far away provinces.
No system is perfect, but if we really want a semi accurate national classification, we really need to move towards a national classification system which has its own problems and costs associated with it; we would probably end up having to include implementation and administration costs which would end up being like the ICS fees that nobody likes to pay. I don't see a truly effective and equitable solution given our current position.