Allow me to provide disclaimer: all electronic voting systems can be tampered with.
Here is some info on optical scanners, and also a link for problems with voting machines by vendor (including Sequoia)
For problems by machine,Sequoia, Diebold, ES&S, Microvote, Unilect etc see bottom of page:
http://www.votersunite.org/info.aspCOMPARING OPTICAL SCAN TO DRES:
However, ballot stuffing would be more obvious with optical scan than with paperless DREs.
And, most states don't bother to make sure that voting data is reconciled with poll books.
OPERATIONAL COSTS OF DRES ARE SIGNIFICANTLY HIGHER THAN OPTICAL SCANNERS
STUDIES SHOW THAT OPERATIONAL COSTS ARE HIGHER WITH DRES THAN OPTICAL SCANNERS
Counties with DREs would save money by replacing their equipment. In a few years time the counties would
realize a savings that would more than pay for their new system. Costs include climate controlled storage,
greater costs for testing, require more poll workers, etc, you need at least 10 times as many DREs as
you need optical scanners. When a DRE breaks down, lines form. If the optical scanner breaks down, people
keep voting. While DREs do not use paper, any savings from not using paper is completely outweighed by
the gigantic operating costs that are incurred in using DREs.
http://www.votersunite.org/info/costcomparison.asp ACCURACY STUDIES OF OPTICAL SCANNERS VERSES DRES
North Carolina Study indicating that optical scan machines have the most consistent and
lowest undervote rates of the various technologies used this past election. 2004 report
http://www.cs.duke.edu/~justin/voting/totals.html DREs in New Mexico dropped votes 5 times as often as optical
scanners did: Nov 2004
http://www.votersunite.org/info/newmexicophantomvotes.aspFlorida study indicating that DREs had 8 times as many undervotes as optical scanners:
July 2004.
http://www.verifiedvotingfoundation.org/article.php?list=type&type=26 The Paper Ballot Optical Scan system, which includes 1 ballot marking device to assist the disabled
at each precinct. New models of optical scans have excellent features such as:
*alerts voter of undervotes or overvotes
*can record precinct data for absentee or 1 stop voting
*ballot on demand - this means the printer can print out an absentee ballot on demand
the printer can print 30 pages a minute. This is less expensive for the election authority and also more convenient.
*the ballot marking device called Automark has received good reviews from the National
Federation of the Blind.