I was considering buying the Xeon and x58 board a few months back and what I dislike about the X5650 option is that some X58 boards have horrible power usage (others not so much but still nothing like 1150), the chipset does not support current Sata/USB (you either use addon cards for that, or find one of the rare boards with it), most boards are big and complex, and by now pretty old, making reliability a concern, for me at least, also you basically have to OC these CPUs, because ST performance for sub 3 GHz nehalem is not that amazing compared to Haswell, and it requires a decent cooler...
now looking at the 4570, you can run it with very basic MBs (even sub $50) with current sata/usb, power usage is nice, you can run it with the intel cooler, small case and never worry about it again, no OC or anything.
the 4570 is a great performer for general usage and gaming, the X5650 is much nicer for video and rendering work, but with some OC should also be quite good for gaming.
if I owned a x58 board and had some old 920, I would definitely buy the X5650, but I decided against start building a x58 in 2014, for the reasons I mentioned... others might see it differently.