Not really. I'll say this: I think 90o triggers feel marginally nicer as they have a more clean break when you go to pull the trigger (generally not down to the overall design of that perpendicular sear engagement area, but just better materials and quality control than stock units), but the difference is negligible and doesn't really justify the price tag if that's the only reason you're buying it.
On a stock, 45o trigger the engagement area is small because stock springs don't wear the sears much. The point of the 90o was to increase that contact area, thereby reducing wear on the sears overall - allowing one to use a stronger spring without risking undue wear on the sears. This is one of the many reasons why just throwing a powerful spring into a stock sniper rifle is a bad idea, yet people (unfortunately usually new players) do it all the time and then have their trigger mech just go kaput one day and it starts slam firing.
So in short: Don't bother. If you do, go for the cheaper offering like the Airsoft Pro as I've found it just as good as the PDI one (not tried the LayLax or Action Army or others so can't comment on them). Sell on the spring and piston you get with the kit. There are better ways to spend that £45 - put it into your scope fund, for example.