I see a reason why you have put SX4 in your wishlist and i feel its very much justified.
The purpose,still not too sure of comfort level compared to Innova considering a huge difference between the two.
But yes Originally SX4 was created as an offroader by SUZUKI,So no problem there.
It indeed is a sterdy vehicle.
Well Innova might not give you a feel of sedan,nor does interior feel so appealing specially the dashboard.
Having a longer wheel base is both advantage as well as problem for Rural drives.
Sx4 will suit you better if you dont wanna use it for carrying huge loads unlike Innova.
I am unable to suggest you here,my apologise to you.
Probably because i dont see any need to compare both vehicles.
But beacuse you had have fair bit of troubles in the past regards to your Diesel enines,well SX4 wont drag you to Service station for mechanical faults for sure.
Go check both the vehicles in person at a dealer near ou and test drive both of them.
I am sure you will be able to judge for yourself.
SX4 is a good and safe car to drive on highways considering you are buying a zxi.
Besides Innova equiped with air bags will cost you some fortunne.
I think since you have been driving all diesels till now,try some petrol this time.
Success is not final, failure is not fatal: it is the courage to continue that counts.