bro, you get the fact wrong, old lens can use.. but without AF 

2nd part, i agree with another statement of yours, they have limited choice
unlike sony, which inherit from KM using screw-drive motor make our life easier with giving us the AF-ability on non-motorized lens

add on to it:
all 3rd party lens are reversed engineered from older generation chips, because most of the camera producer don't license their technologies for others..

sources: http://www.lensplay.com/lenses/lens_3rdparty.html

ooops i forgot wat i registered so i am gonna dropin for those which i think its good heahhaehea.....stand also nvm rite

A700 vs A580.

A700 is aging, if u wan physical control, A700. and the quick navi. access to 1/3 stop of iso, commander WL flash with F58 (if u dont know what i just said, then its not meant for u)

otherwise, A580 new tech win in many ways.

i. MP = more
ii. iso = cleaner vs A700
iii. multi iso = even cleaner, a good add on option
iv. more AF point = 11 in ovf (4 become hidden assist for center point), 15 in QLV.
v. ohhh QLV, the best thing of DSLR. A700 doesnt have it
vi. better LCD and u can flip for low/high angel shot.
vii. back to AF, it can do better AF lock at low light (tested with gouki with his A700 vs A580)
viii. 7fps? important?
ix. auto HDR is really good feature for landscape and low light interior shooter!.

you mean her body

:''''(

i think my SSS gonna die soon... now when taking long exposure (> 2s) got sound.... FML