@lisa_tos posted a positive experience here in 2011:
http://neurotalk.psychcentral.com/thread153637.html

She got this unit:
http://www.amazon.com/Saunders-Cervi...dp/B002BUOLNY/

One of the reviewers preferred it over the ComforTrac, but his largest issue was his larger size which may not apply to you.

Getting back to neurotalk forums, there were also non-rewarding experiences described in that thread posted by people who had used different tools.