I know! They were both sitting there and I thought time for a few pics!
Hmm how they stack up? Tricky as any comparision will likely turn into a which one does what better, which will be a little unfair to the 400!
Bearing in mind I'm about 6ft and not particularly skinny, I think the 750 is actually easier to handle as I fit it better than the 400. Much less leg folding required to get feet on pegs from feet on ground etc. Again, I find it easier to climb all over the 750 as I'm less scrunched up.
Traffic-wise (filtering etc) the 400 is for the most part easier being thinner, however the larger bike sits you a little higher and the easier lower down power lets you pass traffic much less frantically. Pro and cons for both I think.
Brakes are about as good on either. Going from braking to turning is quicker on the 400 but more stable on the 750, which also has better stability during the turn. Again, both have their strengths and this is a result of the weight, or lack of it. The 400 is more work but probably more rewarding.
Power obviously the bigger bike wins. This also gives it the win on motorways on both cruising speed vs revs and overtaking grunt, which is driven home by the better wind protection (bigger fairing) and roomier riding position.
Saying that, it's possible to do distance on the 400 but I HIGHLY recommend getting a higher screen if you're anything like 6ft.
Running costs I'd say the 750 is obviously going to cost more but it's probably minimal, for me anyway. The difference in tax isn't going to break the bank and the difference in insurance for me between the two is about £30 (I'm 31 yrs old so insurance is now pretty cheap too). rear tyres etc may cost a bit more on the larger machine but again we're not talking a huge amount of extra cash.
I'd say the 750 is generally a better road bike. If I was going on track I'd take the 400 for the easier access to extremes of cornering (stability not really a major plus here) and easier to explore the limits without sticking it into the run off
