When its up and running, you'll be glad of EFI. I've not delved into it but the hotwire system isn't massively complex and mine seems to run pretty sweetly. Carbs can be simple but I've read that even a small 390cfm Holley can be a bit over the top for a 3.9 rv8. After all, you find them on mild small block chevy and Ford motors (5 litres or so). I have a feeling that it would need as small a set of jets as Holley provide for that carb and whilst an easy job, that will cost you a few quid to get hold of.
Nothing wrong with twin SUs but you'll never get the mpg, power or reliability in a range of temperatures and conditions as the EFi setup. Even if the EFI went wrong, you can replace all the major components for very little second hand.
People like carbs because there are no sensors and its all mechanical so easier to diagnose a problem, fair enough, but they are an old technology and not as suited to a daily driver as EFI.
Now there is a question over whether a carbed motor sounds better? I have no idea, but some recon they do sound better?