Thanks for all the replies.
As I already have a GNS430 (upgrading to WAAS later this year) I only need a second com to remain IFR compliant. The sets mentioned all have great features (world wide data base etc) but in essence all I need is (preferably) a minimum of 10Watts power and the ability to select a frequency.
I think the ICOM will be my choice as with an adapter it will 'plug and play' into my existing KY197 rack saving on labour, and it should pan out at around £1500 with a 20% rebate from our generous benefactors.
It will be installed by a maintenance company on the aircrafts annual and signed off as part of the radio certificate.