I just went through the same experience. Well, actually, it all started four years ago with the purchase of a used 2005 S80 2.5T for my wife. I was really leary of it, but I was surprised how much it felt like a 240 to drive - solid, beefy, seating position felt the same, etc. Plus, my wife liked it and it was her ride so as they say - happy wife, happy life. So far it has served us well, other than the fact that the headlight bulbs don't last as long cuz they're always on.

So then about a year and a half ago I totalled my nice 745 NA wagon. Whenever I need to purchase a car, there are none that I like available. When I DON'T need a car, they're suddenly plentiful. Anyway, I buckled under family pressure to buy something a bit "more modern" and bought a 2003 V70 NA plain Jane that I knew needed a bit of work. For nearly a year I slowly brought it up to snuff, but all along I felt just the way you describe about the car. Even though it's a close cousin to the S80, it feels completely different - lower, lighter, less beefy - just different.

Then one day I had to haul a bunch of sod from a nursery about 20 miles to my house. The sod was very wet and heavy so I rolled out a bunch of pastic from the front seat to the tail gate and loaded that baby up. I have no idea how much weight I had in there. I said to myself I was going to see what this car is made of. I couldn't believe it! Driving down the road I hardly felt the load.
That was the day that I acquired a new respect for the V70. I always thought, judging from the exterior appearance, that the V70 didn't measure up to the interior volume of the 245/745/945. But I'm thinking differently now - it doesn't seem that much different. I guess I'll keep it a while.