When I went from a 245 wagon to a 940 wagon I was pleasantly surprised by the turbo power and the handling and roominess in the engine bay. The brakes were poorer, but overall I found the 940 more user friendly.
I have 340,00 on mine with 150,000 on the best junkyard 1995 turbo red block I could find. She tows 3500 lbs and with IPD blue springs and KYB shocks in the rear and Bilstein touring up front I find the suspension fine for hauling outboard engines and small boats. Twice I towed a 17-18 foot center console with outboard from Florida to CA. She took it quite gracefully along Route 10.
Once I put on the Michelin "Agilis" class C passenger tires at $160 a pop(increasing my payload rating 500lbs) I discovered the best tire for the heavy Volvo. Tracks very true and seems to roll better. Better gas mileage and the rubber is as tough as iron. They replaced my Yokohomas that wore out at 23K and pulled right despite being aligned twice. The Michelins corrected my alignment problems. They are expensive but I love the thicker and stiffer sidewalls and the extra weight capability is just the security I wanted. That's why Volks Vanagons and Mercedes vans use them.

My question. When and if I replace my wagon should I go with the 940 or step up to the refinement and power of a good V70 wagon. Would I go turrbo with the V70? What would you do?

Look for a worthy 940 and buy it
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89 240 wagon, 94 940, 200K, 94 940, 135K

I'd find another 940.
A v70, or any FWD White Block Volvo, is unfortunately disappointing--nothing remotely resembling the qualities and build of Red Blocks. I've tried them, they seem to resemble VW Passats which are better all around car. I have a V50 t5 with 6spd, and it is not bad car but nothing like my Red Blocks. I catch hell for my view but enough cars go through my hands to form an opinion...
And, 940s are not "heavy": at round 3,000lbs, a Hyundai Sonata or Nissan Altima outweigh the 940... The Volvo just feels heavy, you can come up with your own reasons why....

I'm also thinking about a V70. Personally, I would go with a 5 speed V70 if you can find one. My second choice would be a turbo. However, there is nothing wrong with the NA models. I've had a NA 95 850 wagon (w/233k) now for about 5 years and the power is adequate, but I think I'm ready for something a little faster... You might need a little more power too if you're hauling boats and outboards.

However, if you crave simpilicity stick with a 940. No question it is more DYI friendly. I almost bought one more than once. I am also a former 240 owner. Probably the two biggest negatives of the FWD cars vs. the RWD cars are they generally aren't as easy to work on and the parts are usually more expensive. They really aren't too electronically complex until the 2001 models. Then they became much more computerized. The early V70's aren't too complex, and are more comfortable and refined than a 940. The best year for simplicity is the 1998's. Mechanical throttle, no coilovers (one coil) and very reliable.