The issue I have with the view that schools are 'forced' to use a particular platform is that it is nigh on impossible to do so.
From my view and experience I tend to look at a central LA platform (I'll get on to regional later) as a tool. It can be the principle tool of a school or it can be a complimentary one. Those schools who are the early adopters and have developed their curriculum around a particular product and then have something else thrust at them have to accept that this is an additional tool and not shut down the idea of using it at all.
We also have to remember that whichever platform is being used they tend to have similar functionality, but with different administration, different look/feel and a different hierarchy or structure (a number of these are actually imposed by historical methodologies for T&L or Leadership). A lot of early adopters are used to using multiple tools to achieve the combined end and the cynic in me would say that it verges on political as to why some schools do their own thing and not use the additional tool. And that applies from the LA side too ... they want schools to use what they provide so they have a greater element of control.
The Pros and Cons ... where to start.
I'll start with interoperability. We only have a chance of getting interoperability in place if there is significant pressure to make it work. This pressure does not come from individual schools (unless they have a lot of political or educational weight behind them) but from LAs and regional groups. These groups may originate from the RBC, they may originate from other areas (SSAT, Becta, Faith Schools, BSF) but it is collective will and influence that forces the change identified by those early adopters. Early adopters have to work with these groups to help other schools, not against them. However, without these schools and visionaries we don't have a base to move from.
Collaboration. Many schools will only collaborate on their terms unless forced to do otherwise. If you have an LA / Regional platform then it has to be flexible and open enough for schools to do this, but with an element of compromise on both sides. Collaboration only works if there is a reason to do so, and more work needs to be done at school, LA and regional level to identify areas that require collaboration. Without wanting to do any finger pointing (but will do anyway) it seems silly that institutes like NCSL do not make more use of LA or regional platforms. I know many groups already have their own solution but very few look to use LA / Regional solutions to compliment what is going on. An area for improvement if you ask me.
T&L ... anyone fancy opening a can of worms? Many schools have particular styles or an ethos that fits in with a particular way of working with students. These often take time to develop and the introduction of yet another element can be viewed as risky. Unfortunately the view of having too many things to use tends to be an adult view. Students will, quite often, make use of anything and everything that is out there. The days of walled gardens is gone as students have little reason to use a limited toolset provided by an educational platform. The key thing is to educate learners when it is appropriate to use these different tools. If the school is not using an LA provided platform they are restricting some of the tools available. I can understand why, but effort is needed on both sides to make it available and usable (a key thing ... a platform is just a tool ... you need a reason to use it!)
Communication. Whatever platform you use, whether as a school or an LA, you need to remember that one of the principle functions is communication. This brings up the issue of multiple communication methods. A single platform only works if there are agreed methods of communication and they are easy to follow, easy to use and communicate useful (that word again) information. If it can pull / push information to other platforms then you are again make life easier for collaboration too.
Best value ... you only get best value if there is a large uptake of the platform. There is little point a regional / LA platform being purchased and saving 50% on the price if only 40% of schools use it. Unfortunately it is nigh on impossible to make the investment and then have a mass roll out and expect everyone to use it immediately. A phased approach may fit into our needs better, but it may not fit into a best value financial model ... until you change the model not just to be about cheapest.
Finally, it doesn't matter what is chosen now, there is always something better around the corner. We have to learn to make a choice, go with it and accept that there will be times when we are slightly behind the curve. To make sure people do not get far behind the times we have to start planning as soon as a platform is there. In a school this is slightly simpler to do, but in a large platform there are more dependencies and wholesale change / improvements becomes more difficult. This is where the early adopters come in again ... we have to rely on them to help us making the right choices.