Rob M, don't forget Signature Switch Co. and OscaleTurnouts both offer ready to lay P:48 turnouts and crossings in a few common frog numbers and rail weights. They come in various levels of detail and the basic ones are about the same cost as current Atlas O scale turnouts.
Anthony, to offset the general lack of good loco models, I do feel there are some things O scale and P:48 can do better than smaller scales, such as the sense of mass and momentum, plus sound thanks to improving DCC decoders and speaker design.
I worked around the lack of "highly-detailed yet affordable" modern Diesels on Oscale by modelling a freelance modern shortline in O scale 2R. Not ideal but at least I have more flexibility to run older locos and it's somewhat affordable. 
My rolling stock is mainly Atlas O with some Weaver and a few MTH and even K-Line cars.
To give an idea, below is a clip of 5 of my plastic locos with metal chassis and brass trucks, DCC and sound: 2 x P&D F Units and 3 x Red Caboose GP9s. Not all that accurate compared to the best modern HO plastic locos, but they run well and sound OK I think.
The CP and CN ones will be patched out for my shortline eventually. To the left of this scene is a 36" radius hidden curve which they and all my freight cars up to 72ft CenteBeams negotiate with ease.
I hope you will consider taking the plunge into O scale 2R or P:48!
These days even the lower quality dual-motor drives in Atlas locos that were designed for 3 rail can be made to run fairly well thanks to the latest decoders such as Loksound 5:
