Just a question, what is it exactly you are after with the upgrade, as I suspect that the difference between the Rotels and whatever else you could get, is in the details and realism - often more personality traits than anything else, not really in measurable - as in low frequency or high frequency extension. If the price of interconnects make you pale, you are over-invested in them - relative to the components you have.
Really I don't think unless you like the look of a integrated versus a separate system, you should avoid one or the other... just go with what sounds best. I don't think the one needs to sound different to the other, but some do and the one you like may just be a separate system.
Just my 2c a good amp can make a huge difference, as can a source, as will the speakers. You really have to think where you want to go with the sound before you plunge. And I must say you need to figure out what will make the biggest changes in your system.