AFAIK the Icom A4 is not CAA approved in the UK, I don't know why.
The Icom A3E (I don't have the VOR one) is exceptional. I use one linked to an external antenna and headset adaptor for air displays and it's performance is outstanding.
The original batteries (NiCd) need cycling to keep them going but will rarely last more than 2-3 years. Get them re-celled with 1000mAh MiMH cells and they are much better. In the UK, Combat Alexander (
www.combatalexander.co.uk) will do them for less than £30. Outstanding value and well worth it.