I don't know about DPP4, not sure is it is supporting the 50D yet, my only option being stuck with a Win XP computer at the moment is a 3.x version of DPP, and let me say right now it is vastly worse than LR at dealing with both highlights and shadow detail. Personally I think even the previous Process Version, think it was PV2010, was better with highlights than DPP3! Shots that show plenty of highlight detail, with zero clipping in evidence, in PV2012 are simply unusable in DPP. Also since I have a range of older cameras, and of course image taken with them when they were current cameras, a RAW processing workflow system that cannot handle ALL of my image files isn't a lot of use to me.
That's the other thing, LR is so much more than a RAW processor. It is a comprehensive workflow solution. It covers everything from moving your images from the camera, organising them, in many and diverse ways, RAW processing with one of the top three RAW processing engines, based on features and quality of results. It then make handing off the image for additional RGB based processing steps in a pixel based image editor very easy should you need it, and then brings those RGB pixel based images back into LR for including in the aforementioned organisational system. It is then very good at producing your final output in again many forms, both digital files, and prints. So much so that for the last four years I have not kept a single finally outputted JPEG file on my computer, that was not being used as a desktop wallpaper.