You should get on fine with the Suzuki 140 4-stroke engine - having owned one now for just over 2 years, my engine has been faultless. I started it last weekend in a fishbin (cos the dustbin isn't big enough) and it hadn't been started since November last year - as usual, it fired straight away without hesitation. As for fuel consumption, try searching for suzuki 140 fuel or something in the search - it's been discussed a few times now I think
The Humber's are great - I've been out on 5m assaults last year, as well as my own 6m destroyer including a 9m ocean pro a few times. At the yacht club we use the small assaults with 40hp suzuki's - they are very nimble which is great, but the lower bow does mean it is a wetter boat in chop. My boat is surprisingly dry - after my first rib, and talking with a few people, I assumed ribbing was one of these things where you got wet everytime you went out. I can quite happily go out on my boat and come back bone dry provided it hasn't rained.
The ocean pro is better again (I should have bought one) - I prefer the higher bow and it's a bit wider than mine for the same size too.
It certainly might be worth having a look at Alex's Humber 6.3