Hi Dan,
My 2007 V8 now has 320,000km on it. Transmission was rebuilt at 180,000km just after the previous owner's son got his red P's... and I believe that the snapped transmission parts may be related to the tyre wear...
Previous owner spent $35,000 total including "repairs" and depreciation for a total of 80,000km. I've spent way less than that for the next 140,000km, but do all my own work.
The ownership experience between the 200 series (simple and tank-like) doesn't transfer to the XC90 generation (extremely complex but way more capable). I don't think they're too bad to work on for a modern car, but to work on the AWD coupler or angle drive on the V8 (for example), the exhaust manifolds and front subframe need to come out.
The Yamaha V8 is a beautiful piece of work. However like most Japanese engines the seals for front timing cover and cam covers are rubber which hardens and shrinks. If you find one which doesn't leak oil (yet), then in the next few years it will. It's a fiddly job (which the previous mechanics completely botched...) and the gaskets themselves are fairly cheap...but you'll probably need onjector seals, inlet manifold gaskets, PCV valve and hose, serpentine tensioner and idlers..."whilst you're in there" - around $1000 in parts.
I've just had to replace an O2 sensor (after 300,000 who's complaining ?) but it was $350 for the part and there are 4 of the buggers...
The TF80 transmission is nothing like the wicked GM 4-speed in the T6 models, but it has an alloy valve body which gets chewed up if the fluid isn't kept fresh and Volvo seems to use the torque converter lockup clutch a lot more than other manufacturers with the same transmission (Mazda CX-9 for example) and on two other V8s which had 100,000km of city driving I've been trying various cures for slight torque converter shudder. (Mazda have the same problem, by the way)
(The transmission is Aisin Warner (ie Toyota) and the engine is Yamaha - it's a very Japanese Swedish car...)
Are you thinking of servicing the XC90 yourself ? If so, there are a number of "discovery opportunities" - no dipstick for the transmission, for example. Suspension parts seem to wear quickly, but are very easy to replace.
Because the XC90 is complex, there are so many opportunities for parts failure. Steering angle sensors, wheel speed sensors, ABS units, climate control sensors...plus 16 or so separate computers communicating they're all part and parcel of new car ownership. The radio isn't in the dash but in the roof at the back, and the amplifier is under the driver's seat...connected by fibre optic. Buying an XC90 with no working radio (AM anyway) isn't the easy "Supercheap" aftermarket radio affair it is on the 200 series !
The key to a good ownership experience will be your expectations, and finding somebody (or yourself) who can sort out any problems correctly.
The previous owner of my car was quite upfront - he thought it was the worst lemon he's ever owned (although he loved the versatility) For him it was the least reliable car. For me it's been the best car I've ever had, and not excessively expensive (for a modern car).
I don't want to put you off - they're fantastic cars. However I'd like you to know what you're potentially getting into - unlike my experience ...
All the best, Nathan