Personally I did a slow taper (though probably not slow enough). I was on methadone for about a year and a half, I think my dose was 80. I took about 6-8 monthes to slowly taper and felt pretty good untill I got completely off. I struggled a lot with sleep and anxiety for several months, but its hard to say how much of that was withdrawels since I was smoking absurd amounts of weed at the time, which, in case youre wondering, was a terrible idea. I wasnt working during this period but I'd imagine it would be pretty damn difficult to hold down a job.
So, since you dont want to take a lot of time off work I'd suggest tapering your methadone dosage to about 15 and then switch to suboxone, and then ween off that slowly, just because Im pretty sure suboxone has a significantley shorter half life.
Just keep in mind that the real withdrawels wont start untill your completely clean. So even though you may feel alright now, just remember to take it slow or else they may kinda hit you all at once like they did with me. Dont worry though, detoxing is not as bad as some people make it out to be (I think us addicts like to be dramatic). Ive been off methadone and all other opiates for almost 2 years now and my life is immeasurably better.
Best of luck, and I'd suggest joining a recovery group and going to meetings if you havent already. It really helps to have people you can talk and relate to, even if they may not be recovering methadone users themselves. Believing or not, netorking with people will help with the mental and physical withdrawel symptoms.
I remember I felt so accomplished and happy when I finally got off that stuff, even though physicaly I didnt feel so great. It was truly a "natural high" that stayed with me for quite a while.