Mal,
I haven't used Dropbox before, but just so long as there's nothing complicated involved in sending files, I could let you check out a couple of full-sized JPEG or raw files (If you like, PM me the particulars and I'll see about sending you a few files in a day or so)
Manual focus isn't one of my favorite points about this camera: Basically you use a couple of buttons or the control wheel for the task, but the button control starts off glacially slow, then builds (too much) momentum, while the wheel isn't quite as grippy as I'd like, and it's too easy to accidentally click and bring up some other function.
Manual exposure is "adequate", and live histogram is a plus, but again, the camera's got a single non-stellar control wheel. Fine for relaxed and deliberate shooting, but not the most enjoyable way to use the camera. For general shooting, Aperture- or Program modes work fine, and actual usable aperture range is quite limited anyhow. The camera's automation favors lower ISO and moderate shutter speeds, so for bird shots, I find that Shutter-Priority works best.
SX50's image stabilization is nothing short of amazing: Even at 1200mm, the IS can seemingly freeze movement for brief moments. This is the best IS that I've ever encountered outside of Canon's own binoculars. Have been delighted to find that I can actually handhold it at 1200mm in early afternoon light, even when it's overcast.
Optics: Haven't systematically tested for distortion, vignetting, corner sharpness, etc (processing raw files in Aperture) but so far haven't been troubled by that either. Have noticed occasionally heavy blue/yellow chromatic aberration in some high contrast areas, typically tree branches against sky.
Raw files: As you know, the smaller the sensor, the less-plastic they are. Actually gives a bit more range than the camera's histogram indicates, just don't expect to pull amazing detail out of highlights. But I'm pleased at just how good today's small sensors can be.
Overall, a fun camera that can take you places that others don't.
Jeff