It should be common across all the Bitforce SC range. On power up (in the open source firmware) the unit runs a series of self-tests to determine a good operating frequency for a chip and whether the engines in it are working correctly. If they aren't it disables them. Cooling the unit can cause engines to be more stable and clock frequency to be set a bit higher, resulting in a higher hashrate while the unit runs, although there might be more hardware errors.

One thing I have noticed, the power-on self test for the open firmware takes a lot longer than the stock firmware did. I am wondering whether some sort of calibration is run beforehand during burnin and fixed values are set on the various units based on the burnin results. Doing it this way would allow the faster power up time and also a more consistent hashrate irrespective of environmental changes.

For me BFGMiner was easier 

BFGMiner uses FDTI drivers,which work with more devices,IMO,instead of Zadig ones.

https://bitcointalk.org/index.php?topic=168174.0

You can use a bat file like this intead:

Here is a semi blank batch file for bfgminer   
1)Copy the text to notepad and modify what you need then save it as bfgminer.bat.
2)Put it in your cgminer folder and & double ckick to run it.

bfgminer -o http://poolurl:port -u user -p pass

There's more "commands" you can add,even though this link is for cgminer they still work:

https://bitcointalk.org/index.php?topic=28402.0

Scroll down to EXECUTIVE SUMMARY ON USAGE 

For the brave (and very few) BFL SC single owners out there that wish to flash your devices to try and get the last bit of hashrate out of them, I have uploaded 3 different compiled firmwares here:

http://ck.kolivas.org/apps/cgminer/BitForce_SC/BitForce_SC_1.2.6ck.zip

They all try to enable extra engines than the default firmware does, but in addition I have made 3 different speed ones available, they're tagged 7,8 and 9.

I suggest you start with the 7 first, and if your HW error% rate is less than 2%, try the next one up. I have two singles and one worked best with the 7 version while the other with the 9, so each device will be different.

Remember to put the pins right when connecting your AVR dragon to flash it, and note the different device that Amtel Studio tells you the single is (compared to the Jalapeno) and change your settings accordingly.

If you don't know what the hell I'm talking about, then just ignore this message, since it assumes lots of prior knowledge about flashing the Jalapeno.

BFGMiner was really easy to get going,as I have BEs running too,just follow these instructions 

https://www.btcguild.com/index.php?page=support&section=blockerupter

Heres a sample "target" shortcut:

"C:\Users\pcname\wherever\Eruptor stuff\bfgminer-3.1.1-win64\bfgminer-3.1.1-win64\bfgminer.exe" -o http://stratum.bitcoin.cz:3333 -u username -p password -G -S all --icarus-options 115200:1:1 --icarus-timing 3.0=100

Might want to make some phonecalls or check your mail... I saw this on track and trace for Latvia:
Latvijas Pasts: CJ422490240US    
Track at official postal site
Date   Zipcode   Location   Event   Weight   Additional
20.08.2013 00:00       Šķirošanas Vieta - Rīga    Arrival at international place of exchange       
20.08.2013 00:00       Muitas Iestāde    Into customs       
21.08.2013 00:00       Šķirošanas Vieta - Rīga    Arrival at international place of exchange       
21.08.2013 00:00       Šķirošanas Vieta - Rīga    Sent to delivery office       
22.08.2013 00:00   PP-4601    Pn Rēzekne - 1    Arrival at delivery point       
22.08.2013 00:00   PP-4601    Pn Rēzekne - 1    Recipient advised to pick up the item       
   

interesting is that you will be screens of all my account pages. i just wont do that.