No issues with Linux.
1.65V RAM works ok on sandybridge boards also. Just set the RAM timings and settings manually in the BIOS to what is printed on the side of the RAM sticks.
Is the Asus board only compatible with certain hardware, in this it has a list of devices http://dlcdnet.asus.com/pub/ASUS/mb/LGA1155/P8H61_M_LX/P8H61-M_LX_Device_Report.zip I mean a why would 1 HDD not work & the other would?
LGA1155 is better.
The CPU's are faster.
The socket is newer and more future proof for Ivybridge etc.
Compare a similar priced i3 540 vs a i3-2100 - http://www.anandtech.com/bench/Product/289?vs=143
No overclocking - http://www.overclockers.co.uk/showproduct.php?prodid=MB-172-MS&groupid=701&catid=5&subcat=1907
Overclocking (with a K CPU) and Z68 features - http://www.overclockers.co.uk/showproduct.php?prodid=MB-343-GI&groupid=701&catid=5&subcat=1990