I'm sure there's plenty of single turbo Supras running great, you just don't get to hear about them.
The only problem I've had with mine was when the bearings on the state-of-the-ark PHR1 turbo died for no apparent reason. Now the turbo has been replaced with something a little more modern it's brilliant.
I really should pull my finger out and get the map adjusted to allow for the larger turbo and the different exhaust the car has now compared to when it was mapped, but it drives great, always starts, never overheats, etc etc. What more do you want?
Having said that, there aren't any cheapo parts on mine, as far as I know. It's all brand name stuff (Motec, Garrett, HKS, Power Enterprise, HKS, HKS, HKS) no eBay stuff.
For the record, Dan Turner mapped my car last and I'm very happy with the work he did.