Thanks for the info Robin, initially I had thought Raymarine all the way, but looking at the Simrad products I'm not so sure. I think I will try and find a dealer for each to have a proper look first.
There is such a wide range to choose from and I guess its down to cost / benefit at the end of they day.
I'll keep an eye on your blog to see how your updates are coming along and hopefully you don't mind the odd question along the way.
Nowt wrong with "if it aint broke dont fix it" Smoggy.