First of all....I would question whether a 2005 transom was designed for four stroke motors. I seem to remember back then, that the larger fourstrokes were just becoming available and we normally called Proline directly to discuss what we were going to do to be sure that the transom could handle the additional weight.
It appears that the boat is rated for 300 HP....see owner's manual
http://www.prolineboats.com/Images/Archives/OwnersManuals/2005/24and25_Sport.pdf
I am not sure if the manual is the exact one for your boat.
Anyway...both are very good motors.
I don't have my pricelists here, but I would imagine that the Honda is more expensive...due to higher horsepower. I am sure your dealer can tell you that part.
Both have 40 amp charging systems
Suzuki is about 80 lbs lighter than the Honda. That may almost make up in performance for the difference in horsepower.
If you do your own maintenance and adjust your own valve clearances.....the Suzuki is adjusted using shims (are a pain to do)...the Honda is adjusted with a screwdriver and a wrench (much easier).
The timing chain for the Suzuki is totally immersed in oil, below the powerhead (essentially in upper part of the oil pan). The Honda is oil lubricated on top of the powerhead.
In the USA, both have good warranties. If the dealer is participating, the Suzuki has 3 year plus another three for a limited time. The second three years is a declining warranty...which means it covers less over the three year period.
The Honda has a 5 year, no declining warranty.
The Suzuki 140 HP has been around and improved since 2002. The Honda 150 HP since 2004.
The Suzuki has a different gear ratio which enables it to turn a much larger prop and seems to have a lot higher torque for takeoff. Just my opinion.
I have not had a customer unhappy with either motor.
The other question you should have.....is there a servicing dealer near where you will keep the boat? That is very important if you do have an issue.
I know I didn't give you much direction either way...but I would make you decision based on the following:
1. Weight and Horsepower that the boat's transom can handle....Safety first.
2. Price
3. Servicing Dealer location
4. Personal experience or preference for either brand
5. How soon can you get the motors installed.
If you have not already done so, you might want to post the same question on the Suzuki Forum.
Just some thoughts.
Mike