Just found this blog and I'm new to it... but I think this may be of interest to some of us who know the value of what we are doing!... then again... it may have already been posted or may simply be common knowledge. As I said... I'm a noob here!
Anyhow... I've been looking at the difference between banks that only take loose change and then roll their own coins vs. banks that "buy/exchange" customers rolls and I've found some interesting finds and helpful hints (although I plan on looking into this in more detail soon):
1) There seems to be a slightly better percentage of Cu in customer rolled rolls as opposed to bank rolled rolls. I've found a few percentage points higer. I'm going to do some stats on this later this year... so this is more of a hunch right now than anything (since I can't verify if I am statistically correct in saying this... and yes... I am an Engineer so statistics are IMPORTANT to me when making claims). Anyhow... I believe this is likely due to the fact that these rolls have likely sat around in jars for many years and then traded into the bank for cash. This means that these rolls contained the Cu ratio of earlier years as opposed to real time ratios. Think about it... each year more Cu is taken out (by smart folks like us) and more zinc put in by the Feds into circulation. This means that the percentage of Cu is decreased annually. Therefore a bank customers penny roll should contain higher percentages than an average bank rolled roll since it contians the Cu percentage of previous years in it. The morale of this... the older the roll you can get... the more Cu it should contain! More on this in the future...
2) After buying some customer rolled rolls at at Forrest Street... I made a great strike! I found over $50 in penny rolls that ended up being 98% Cu coin rolls! But.. there were VERY SMALL amounts of modern coins mixed in (I even found ONE 2009 penny). This tells me that they had been rolled recently. Any one else come accross this? I think that it may have to do with the fact that I live in a VERY RURAL area and that these may have simply been a local who had been saving their pennies for a while and decided to cash them in and simply needed the newer change to complete some short rolls. I'm guessing the person stopped collecting in 1982 since this was the bulk cut off year (in other words there were LOTS of 82's and VERY FEW 83's and on). I dunno. Could of been someone simply turned in their hubbies old copper hoard.
3) The customer rolls were done using shotgun rolls. Therefore... after sorting them... I was able to put the Zincs BACK INTO the shottys and saved me from having to use my own papers or from having to go get them rolled at a bank. Another bonus.
Hope this helps someone!
. I had gotten skunked once with customer rolls. The bank called and said they had a large deposit of pennies dropped off and asked if I wanted them. When I searched them they were all zinc 
with the exception of some Canadian which I attribute to the prior collecters lack of knowledge pertaining to copper content. After that lesson I always crack open a few rolls to assure they are worth sorting.