Deceptive NTR figures since D4F and finspreads price the dec 03 spx differently.
With d4f your stake is per tick i.e 1/10 of an spx point.
With finspreads your stake is per point.
So assuming £1 stake, D4F's ntr covers a 10 point move. Whereas Finspreads covers a 50 point move. So, d4f is better value with regards to both margin requirements and spread.
I'm reluctant to suggest that one is better than the other with regard to short term trading. I have accounts with both simply because neither of them is sufficiently reliable to warrant only having a single account.