I recently bought an S570, and am seriously impressed by it. I went for the 570 over the 370 partially because it felt a bit more substantial than the featherweight 370. Its tempting to open it to see if there are any component changes, but TBH I doubt it. The fact that the £99 370 seems to have vanished, made the price gap close enough to justify it for me (got a MR 570 for £179 from RS)
I dont have (or want) 3D, but I wanted the wireless despite people saying it drops out streaming over wi-fi. I have had no such problems, so I can only assume peoples connections are slower than they think. The manual says minimum 2Mb broadband, though iPlayer/love film stream at less than 1Mb. Ive tested mine and its about 5ish. If it were me, I would have provisions for an Ethernet cable just in case.
I thought the quality of the iplayer / love film would be pretty ropey at such a low bandwidth - but it's actually really good. I also have iPlayer on my Humax FoxSAT HDR, but it looks a fair bit better than that.
These new Sony BDPs are incredible value for what they offer. It would be a shame to let your broadband compromise what are (and will be) very useful secondary functions.