Personally, I'm seeing a lot more people deploying LTO (linear tape-open) than SDLT (super digital linear tape). While I have not heard any specific issues with SDLT, the market seems to be adopting LTO at a very fast rate.
For more information on LTO, check out http://www.storage.ibm.com/hardsoft/tape/lto/prod_data/ltovsdlt.html. This a great link for comparison information.
Hope this helps.
This was first published in October 2001