I think the trust system is a brilliant idea. I'm a relative Newbie and made my first transaction via a Bitcointalk member today and the trust system increased my confidence to trade. It was also nice to receive positive feedback for my part of the transaction. 
Looks like one of you used the feedback system incorrectly. The risked BTC should really only be used by the person who risked something. The person who sent first would be the one who risked BTC, the second sender didn't risk anything because they had already received something, and they were just finishing the transaction.
I sent first, £10 GBP. I then received what I'd asked for which was 5 Litecoin. I used BTC-E for the conversion of 5 LTC to BTC which came out at a risk of 0.12 BTC, so I entered this figure in the risked BTC box. Is any of that procedure incorrect?
I believed you did it correctly, because you risked money. So your feedback with him would include what you risked. He's the one that took no risk with you and was incorrect. He already had cash in hand before he sent anything.