would second that about the crypton,they have been nothing but trouble and s**te for 20 years now,we now use 1 omitec+1 sun.had to use two different makes to avoid getting stuck with two turkeys(again!)sun aint been too bad considering the use it gets,the omiscan is reasonable but slow as arseholes.
If you want it for just MOT emissions, go for the 350, far less to go wrong simple to use and mine has been very reliable. I had a pc based crypton before, nowt but trouble, never again.