Unfortunately having had a bad run with Baker, Schlumberger will...

Unfortunately having had a bad run with Baker, Schlumberger will be in no hurry to bend over backwards giving IVZ a "competitive deal" since there effectively aren't any competitors.

Some thoughts based on my experiences:

Baker - I don't think anyone here or at IVZ would be comfortable having them back.
Weatherford - I've always had pretty average service from this mob and after they filed for bankruptcy a few years ago their service really went downhill.
Halliburton - I've worked with them on quite a few projects and can't say they've ever impressed me.
Schlumberger - If you can handle the attitude they generally get the job done and their tools are generally ahead of the other companies in terms of reliability and capabilities.