Has anybody had any experience dealing with these vendors for performance testing/tuning? Or can anybody recommend any other Vendors that do performance testing i.e response times, resposnse codes, virtual/live agents etc
Are you looking for someone to conduct the performance testing for you? If so, you might want to contact James Pulley at PowerTest: http://powertest.com/index.html. You may be familiar with him from this forum...
SoCalGal - Defender of end user response times!