HL share price improver

puzzledinvestor

I've done a few days ago a quick comparison between 2 brokers (HL and X-O), and while for large caps, the results were identical, with some AIM stocks there were significant differences, e.g. 15.4 vs 15.8p and 43 vs 45p. For the first one I got the same results in 2 different days.

Given that the difference was much larger than any saving you can obtain by lower dealing charges (and more than doubled the spread!), I'm surprised of not being able to find more information comparing results from different brokers, with a larger sample of stocks and brokers (or at least number of market-makers or RSPs as coastline gives for Barclays). It would be a very helpful information.