Hourly pay means that time worked equals time paid, for the most part. That is, there is immediate gratification for engineers that work overtime because they will be paid straight time for their OT hours.
Cons
You are always subject to whims of the market and of your clients. Sometimes an industry downturn will mean you need to find a new job!
There are not many at the moment other than there are some great people. Sadly, these are being drowned out by the bad.
Cons
Do not care about their people. Salaries are no longer competitive, neither are benefits packages. Ruthless, narcissistic, egomaniac, toxic work environment.