Hey Exit,
In my job I could get paid per hour, per job, or salary. There might be benefits to any of these methods, but you can back out any payment method to equal any of the others.
So no matter what you decide, back out the salary to the per gig rate. How many times a week will you be playing? How much are you making per week?
Belle also has a point. If you have a lot of regular gigs that you can get paid more for after considering the above, stick with that. If the salary pays the same as a gig, look at it that way and negotiate accordingly.
Hope that helps.
D