I can't speak to the V61's (couldn't justify the price either), but know that tri-ribs were a nite and day difference for me. Turning in loose soil or simply keeping a straight line when pulling a plow have both become dramatically easier vs the Carlisle turfs I was used to on my GT's. My experience is with the narrow front tires though also. The worst tire I've personally experienced in the garden is the 6.8x8 turf. Just seems to slip, slide and push all over. I'm now hoarding narrow front rims to convert future 6.8's to a narrow footprint. MHO =]
Weight should help regardless of the tire, and I have been throwing 46# on the front when tilling, but haven't tried it for plowing yet. I don't get that light feeling in the steering with only a plow on the back.
I've noticed no downside to the narrow tririb on turf or elsewhere...