I was an SQF Auditor and was an employee for one company for about 4 years and then went independent when I decided to transition to being an SQF Consultant.
If you work for a company you are bound by when and where you are sent to do work. The company I worked for required that I made a statement every week that I worked 40 hours (the standard work week in the USA) when in fact my working hours were more like 80 hours - this included preparation, driving and flying on company business, setting up the corrective actions for each completed audit and then having to review the submissions from the facilities that were audited.
A typical week meant preparing, packing up on a Sunday, heading to the airport on a Monday morning around 4am, flying on average 2-3 hours (sometimes 5-6 hours), getting a rental car on the other end, going straight to an audit location, leaving in the afternoon and checking into a hotel - getting up next morning - checking out and going to the same audit location, completing the audit, drop off the rental car and repeat the process again - on Thrusday nights I'd stay at the same hotel for the 2nd audit (given 2-days at each location) and then return the car the next morning, get on a jet and fly home -- on the plane I'd write up the audits and the corrective actions. Normal at home time was 8pm - Saturday's I'd unpack, do laundry, have some time with family and look at my travel pack (the company would fedex the auditors a pack containing needed supplies, tickets, etc).
That was a smooth week.
However, most weeks did not work out that way.
You can make a good amount of money being a employed auditor - but it comes with a bit of stress, you have to be mentally prepared for the rigors of the position as well as travel, travel related and being away from family - if you can balance that out you are good to go.
As an Auditor I was effectively operating as an island, meaning I ran the logistics for myself while on the road, doing flight changes, switching hotels, timing, handling delays and handling stress that is caused by facility personal in their reactions to bad news, or simply personality conflicts.
The company I worked for was initially good for me, but then a change in management caused a slave driving issue and that is when I decided to leave, they had the auditors running 7 days a week for weeks on end and that means you have no life.
I was glad my background includes being an SQF Auditor becuase is compliments my abilities in being a great SQF Consultant.
If you become an Auditor, just remember -- take care of yourself and be sure to be home as often as possible with the ones that matter the most.