To what extent does methylation affect TALEN pairs and CRISPR/Cas9 systems? Are there reports of significant off-target mutagenesis? Kindly elaborate on the pros and cons of these gene editing systems.
In contrast to TALEN CRISPR is not supposed to be methylation-sensitive. Please have a look at this document: http://www.genecopoeia.com/resource/genome-editing-talen-or-crispr/
It gives a nice overview on both methods and compares them.