GNS5870 worked brilliantly. It did take about four minutes to get a signal first time out when I connected it at top of climb. Also had to re-pair it as well but after that it was perfect. Located it as someone mentioned earlier, low down on the number 3 window.
Sadly the prevailing weather combined with night flying didn't allow much active use of it in terms of sight seeing but I was thrilled with how it went.
Have worked out that the iPad will clip onto the pad (writing) holder on the side wall if it's a strong enough clip so no need yet to go with a different solution....yet.
Looking forward to the multiple leg nav function coming.