I use a roller about half the time. For business trips, definitely. My electronics, entertainment, toiletries, and a few changes of clothes goes into my carry-on and the rest in my checked bag. I've discovered that it's awkward to carry much more than that, particularly for long trips where there might be a few hours layover and we want to go out into the city or walk around the airport. And on my flights to Africa, it is almost a brawl to get overhead space, and I'd rather stay out of that and just have a small bag that slips under the seat.
For leisure trips the ratio shifts. I feel like I have less recourse if my luggage is lost, and I'm not wiling to have a missing suitcase cut into my vacation time. It's not usually that difficult for me to fit everything I need for a weekend in a backpack or Western Flyer, and it's fun to travel light. However, I do have an Osprey Ozone wheeled bag, which can be useful too. It is an amazingly light and flexible suitcase. Even when packed full I can easily pick it up with one hand and carry it down a flight of steps, which you can not say for most suitcases.
I think the 10% rule applies here, in that wheel-less bags shouldn't be more than 10% of your body weight. I find this true for myself.