I've got a 4690 and I think you'll find it's perfect for what you're looking to do with it.  They are really nimble in the field, but the steering leaves something to be desired when backing around the yard and into the shed (at least mine does - it doesn't work too well at low speed when you have to do a lot of correcting).  You will not be able to get it spaced for 30" rows with duals on, at least not with the factory rims and duals.  I have 20.8-34's (duals) and I checked the owner's manual because I was contemplating pulling a strip till machine and was hoping to get on 30" centers.  One thing to be aware of, the 34" tires are hard to find since not too many things used them and pretty much nothing does now.  There are basically no used ones out there in any decent shape and the new ones are hard to get a full set because there's such little demand.  I've been needing to replace my tires, but over $1000 each for new bias ($1200+ for radials) and usually they tell me that they can't find a full set.  I'm having a hard time putting that kind of money into a tractor that might only be worth $12-15k even with the new rubber.  I like the tractor, I just wonder when the breakdown will occur that is too expensive to justify fixing it.

Good Luck,

Mike