Unless you can still get them from existing stock. (probably so for D7K)
SLTs, NEX and Nikon APS-C are all underwater now, it the rumors about the factories in Thailand being hit by the floods is accurate.
Sony’s Sensor Manufacturing Plant Hit Hard by Thailand Floods
A77 has more resolution but poorer high ISO performance based on DPR.
Nice bright condition performance though.
You need to be comfortable with EVF too.
They are nice for MF with the ability to zoom in or peaking mode.
However, gain goes up a lot in lower lit places, so it becomes harder to make out manual focusing in such situations (ie. EVF becomes grainy)
Since its an EVF and has a refresh rate will mean that you will have some lag tracking fast subjects.
There is also the need to turn it on, even just to check if a picture is work taking. (ie. can't just bring camera up and peer thru viewfinder to check if subject has photo potential, since it will be black if not turned on)
If you are ok with EVF (and the A77 has the best one to date), then its a pretty nice camera.
NEX are wonderful if you use them for MF legacy lenses and esp so for RF lenses. Peaking feature is nice for MF, though they only bring the user into the ball bark of focus rather than always being tack accurate. Native lenses for the time being are slow, big as APS-C other offerings and not too great in performance. Very ugly contraption IMHO with the large native lenses.
K5 is a great buy right now. MF is fine with properly aligned VF (and/or focusing screen) or else focusing with LV works too, but I'd say its not as convenient as the mirrorless cameras.
The K5 is well built and weather sealed. Built smaller than anything in its class. Low light performance is better than D7K and A77.
AF is fast and responsive.
I certainly won't say its older tech.
Anyway, older tech is more 'sturdy' tech