Your views on this please?

I have a 6 month old baby boy and he absolutely hates to sleep in his cot so he always ends up coming to our bed ( I know I know! all the risks etc etc - and I have made it safe for him as possible but this arrangement still makes me a bit nervous). But if we put him in the cot none of us will get any sleep - including the baby. He sleeps like an angel in our bed!..So I'm thinking of getting him one of those single beds with 2 railings ( and a firm mattress). This way he will still be close to me at night and also get a good nights sleep ( during daytime hes in a playpen - and even sleeps there). I know hes too small for a bed are there any other negatives to this option?...