Pros
Our company has recently been merged with Tetra Tech as a Canadian affiliate. Even though we are by structure on TT's payroll, the management policy and philosophy are pretty independent of each affiliate under the TT umbrella, only with some TT touch added to it. As long as our company's policy does not contravene with that of TT, it is pretty well status quo for all job descriptions, titles and salary. Benefits have been upgraded to align with the TT organization across the board.
Cons
The merger may have left some uncertain taste to some of the old-timers as their legacy of loyalty is now somewhat diminished in the overall picture of TT. Some high performance contractors/consultants were able to receive bonuses before, but no anymore as TT only offers these perks to employees only.