I took my almost 3 year old DS to Babies R Us to try the Volo and the Triumph. He's autistic, so he doesn't communicate things like "comfort" too well to me. I make my decisions by giving him two choices and asking him "which one?"
He tried the Triumph first, seemed to love it, sat back, I reclined it, etc.
I got him out and put him in the Volo. He never really "settled into" it. I pushed him around for a few minutes, but he was perched forward the whole time.
I got him out and then said "which one do you want to sit in again". He went for the Triumph. I pointed to the Volo and said "do you like this one?" and he said "No" and shook his head, then I tried again, and he started to get whiny and kept saying "no no no" (this is how I make sure he really doesn't like something, and he's not just saying "no" to say it). He grabbed my hand and put it behind his knee, and made a "I'm about to cry" face. This is his way of letting me know that something is hurting him or rubbing him the wrong way. I realized that the edge of the seat on the Volo is pretty rough and scratchy. He is a short kid, with a long torso but short legs. The edge of the Volo really dug into the backs of his knees and he didn't like that. The trimph seat is padded and soft fabric. It's a LOT nicer than the Volo, in my opinion, and the price difference is not very much, considering how much more the Triumph does than the Volo, it's an easy decision.
You can get a 2006 triumph on Albeebaby.com for $120, free shipping.
I would say let your child decide. If he/she is comfortable in the Volo, go for it, but I personally found the Triumph folds up more compactly. The volo has a weird wide hood that doesn't collapse well.
For the price difference