This proving to be a very interesting debate. The fundamental principle is that all schools and academies (as public bodies) are held to account on an ongoing basis for their effective use of public funds. This does not purely apply to MIS software but everything a school purchases. Testing the market on a regular basis to ensure that funds are being deployed effectively is simply best practice - there is nothing scary about it and it is part of the everyday running of a proficient school or academy chain.
In my view whether the purchase price (which includes the full price over the total length of the contract) exceeds the OJEU threshold is irrelevant. It is simply best practice to reassure yourself that you have the best product for your needs at regular intervals. Typically you would not select the cheapest option but in procurement speak the 'most economically advantageous' option. Your evaluation would clearly include the functionality and price but also the cost of transition and essentially any end of contract transition costs. The latter (the exit plan and costs) is often forgotten both during evaluation and in negotiating the the contract with the supplier and results in the lock-in that many schools are experiencing today.
The thread of this discussion seems to imply that if you test the market you are in danger of having to change supplier. If your current supplier comes out top in a fair, open and transparent evaluation that is fine. If an alternative supplier emerges then actually that will show the incumbent that they need to up their game. Market testing is proven to drive real benefits in the quality of software and associated services on offer to our schools.
My final point is that although the move to Academy status may be a burning platform in licensing terms that initiates this market testing, those Academies that are 3 to 5 years in will now be coming to a point where they need to formally review their provision once again. Audit Committees will need to be on top of this if they are to apply appropriate governance to the school finances. The cycle continues and it is simply life in the public sector if you are accountable for the use of public funds.