I am not a HP junkie either, which is why I bought my 400. The difference between the 500 paid for the winch.
I like simplicity and reliability, I think more power equals lower long term reliability.

 

Can't remember if the non HO 500 models from 1996 to 2000 were around 35 hp or so or a little lower? I know the Scrambler 500 HO hit around 38 hp,close to what the 400 two strokes put out. Here's a list I stole,don't know if it's accurate or not.
Polaris 850______69.06 hp
Can Am 800 R____67.05 hp (updated 2/13 to 70.5 hp)
AC 1000_________65.84 hp
Can Am 800______61.7 hp
Can Am 650______55.4 hp
Brute 750 Carb____50.1 hp
Brute 750 EFI_____49.8 hp
King Quad 750____49.6 hp
AC Mud Pro_______49.06 hp
King 700_________48.5 hp
Polaris 800_______48.3 hp
Brute 650 I________46.3 hp
Grizzly 700________45.6 hp
Polaris 700_______44.3 hp
AC 700 H1_______41.4 hp
AC 700__________41.4 hp
Brute 650 ________41.4 hp (solid axle)
Grizzly 660_______40.9 hp
Can Am 500______40.4 hp
AC 650 H1_______39.3 hp
Rincon 680_______38.5 hp
Sportsman 500-------35 hp
Foreman 500_____27 hp

 

The 2012 400 ho comes off at 30hp, 35 for the 500.

 

It's too bad that dyno charts aren't readily available for engines. I'd be very interested in seeing the torque curves.

 

I would too. Torque is what I am after.

 

That's one area where i would wonder about the ETX. I'm sure its impressive...but that's one area where the old saying "there is no replacement for displacement" really rings true. Maybe OPT will get a report for you.

Can you swing the 570? I've driven the RZR and Ranger with it, and it moves those quite nicely. It must be quite impressive on a quad.

 

I wont ever own a 570, going Arctic Cat XR 550 next time. Just too many issues of the Sportsman 570 running hot, over heating and melting plastics. These issues seem to be hit and miss, I wont take the chance on it. And thats a shame, I love the value chassis too.

 

The new AC's are nice...but $8599 is a pretty big jump in price. What makes you think they won't have the same issues? A lot of options out there for that $$$.

 

I will have trade in value next time, wont hurt as much. I dont like the XP chassis, so that pretty much takes polaris out of the picture.

 

The cool thing about torque is that you can multiply it, horsepower not so much. There's no getting around the fact that it will have to spin faster to make the same amount of power as a larger engine. If it's clutched and geared right that shouldn't be a problem.

My old Sportsman 450 is rated for something like 29 HP. A flick of the thumb and she screams to 6,000 RPM in short order providing its rated power. A 325 may have to go to 8,000 or more to make the same power, but I don't think the rider will notice the difference as long as it's geared right.