I agree with thebigfitz about the handling of the SRA. Too me, it handles better than the IRS quads I've ridden. Granted I haven't ridden them all, but I feel like there is a weird body roll feel to the IRS quads. It might be I'm just not used to it, or it might just be 'cause I ride mine like a sport quad, LOL. On the other hand, IRS is a softer ride. But I don't think the Brute has a bad ride.
You're right about the seat length of the Brutes. That was one of the selling points for me. You can ride doubles easily and it gives you plenty of room to change your riding position. A backrest makes it even better.
I also looked at the Grizz. I was always a fan of Yammahammer. But I couldn't get one for anywhere close to what I paid for the Brute. I got mine for $5800. I also actually liked the lever-pull diff lock better too. It's not something I use a lot with my type of riding and not having it locked in all the time saves axles.
Between the two you asked about, I'd go Brute for sure for the shear fact that it's a lot more bike. But if you really need the extra ground clearance, find an IRS quad. Otherwise, I know you will be pleased with the 650 SRA., it's a very capable bike if you don't high center. I don't know about the need for EFI up there or snow riding. We don't get much snow down here.