Funny, the Makita rep at Elex told me the 458 was better than the 451. :lol: Same power and the two speed gearbox is more robust than the 3 speed on the 451 (which apparently had a few problems).
I reckon the reps probably just tell people what they think will please them but at the end of the day the 458 is the 451 replacement (if I can believe what the rep told me anyway) and has the same spec (in terms of drilling capacity) but with a 2 speed box instead of 3 (plus a battery level indicator).
I think both are awesome drills so it is probably down to whether you want to save £70 or have two batteries. There is no denying that, if you don't need a 2nd battery, the screwfix deal is very good.......