The Honda Pioneer 1000’s are really stout machines. I have not driven the 1000-5, just the regular 1000. They are very good utility machines, but not the best in the ride comfort if you wanted to trail ride it. They are darn near bulletproof machines. I will tell you that your “backseat” is NOT for adults or anyone over about 4′ 5″.
Another good mention, if you are interested in other brands is the Can-Am Defender. They just released a 500cc version yesterday but also offer an 800 and 1000. Their 4 seater machines are comfortable for 4 full grown adults. They also have far superior suspension, if you care about that. Lots of people say that Can-Am’s prices are so much higher…I challenge you to take a look and look at a comparably equipped machine from other manufacturers and you will find they are about the same if not less in some areas. All while offering a better fit and finish.