Any big spread betting broker comparisons?

If you're trying to compare the dividend payouts between IG and Capital Spreads, just remember that the timing of those payments might differ, which is why it can appear you have differences, even when you don't.
For example for IG, DFBs will be made "at the close of the underlying cash market". Whereas for Capital Spreads, they make "a dividend adjustment to clients' accounts the day on which or before the index constituents’ trade ex-dividend".

If you're comparing spread betting companies, I'd strongly recommended visiting Spread Betting Company comparison, as they've got info on what features are useful to compare, as well as the actual comparisons

You wouldn't be connected with this site, by any chance? Either way, it's far from comprehensive and therefore a bit misleading.
Think there are probably more spread betting comparison sites than there are spread betting companies but I like the fact that this one....Comparison summary - Betting Bible gives a qualitative and quantitative view. What is the point of a lot of these comparison sites giving a comparison of the 'spreads'? They are so different depending on the asset/market!
I can't find any big comparisons of all the biggest spread betting brokers. I was thinking of a SB broker review that had spread sizes as main criteria. I have found one but it only has a few brokers. Has anyone seen a large comparison like that?

IG Index
Capital Spreads
Interactive Investor
Financial Spreads
City Index

There are a few websites out there that tend to have the same firms being compared, I found this one which has all the major players and a snap shot of their spreads. Be mindful that a lot of these firm mark their spreads down ‘as low as’ so might be worth opening one or two demo accounts to get a better comparison.