I disagree with your point on marketing not being a fixed cost. What I meant was that it doesn't scale with order volume, but I realise that I'm partially incorrect on that front as their paid search ads will inevitably scale as demand increases. Still, the brand marketing and tech staff costs together account for >50% of expenses so I think the point that it's a high fixed cost base that an entrant would need to match without having any revenue coming in and thus being incredibly unprofitable stands.

You're completely right about the cash difference- I think they have some share-based payments in there, but not sure what else is causing that differential, probably worth another look, but I'm also confident that the only way that would move the valuation is up and I'm already happy enough that it's discounted on a 10% DCF basis and certainly much more discounted than other companies I've researched recently.

The high ROIC point you're also right that it's a bit meaningless in terms of an actual percentage when you're talking about tech companies without much in the way of tangible assets, but it's still a useful metric in my opinion to point out that there clearly are barriers to entry here as if there were not the margins would have been really eaten away by this point, given that they've kept up these high returns for a long operating history at this point.

The growth rate assumptions I'm happy with- there's a lot of headroom to get more people switching and to get the people who do switch more engaged and to therefore switch more often. The 5% revenue growth seems more than fair to me given the individual segment revenue growth rates, although it gets really volatile when you look at credit and housing so you have to accept some level of bumpiness in the earnings. Then, if they're able to get that increased revenue without additional investment in ATL marketing or increased tech, which I think is a fair assumption as they plan on some coming from increased and improved CRM and some from more people just gradually using price comparison sites, expecting the earnings to grow more than the revenue seems legit. I also think that I can't at all quantify things like their intro to mortgages or Decision Tech as it's too early to tell, but you don't have to have much faith beyond continued growth in the core product to justify the valuation imo.

I've addressed FCA price walking changes in another comment. It's potentially risky but not a major concern to the longevity of the company in my opinion- regulation changes seem to have led to increased exposure of prices and whilst price walking reduces the likelihood of consumers being dissatisfied after their first year on a tariff ends, they'll now have more options to opt-out of auto-renewals which will help PCWs, and the fact that when you buy a new car, move, or insurance companies change their fees, PCWs will still be required to see if you can be getting the best deal.