OP,
I realize you've gotten 3 opinions, 1 from a doctor who does not believe in ADRs which IMHO should be dismissed entirely, and another who only wanted to do yet another discectomy which is also not a great option. So the only opinion that's somewhat good is your ADR/fusion hybrid, done 8 weeks apart.
For me, this would not be acceptable. Both surgeries are difficult and I would not want to recoup from one only to go under the knife again. However, perhaps your doctor will consider Mark's recommendation. You might want to give him a call
GPN Artificial Disc Replacement ADR . He has a lot to offer spinal patients.
I also saw you live in Canada with a confusing health care system which we've heard does not always consider the patient's best interest.
But here's the thing - you know there's always a thing - fusing L4/5, especially at your age, is quite likely going to lead to futher degeneration at
L3/4. This is not a definite but a strong possibility.
I know you're anxious to get this going and put these surgeries behind you but you've pretty much got only one chance to get this right. I wouldn't be jumping into this surgery until further exploring the possibility of an ADR at
L4/5 too. You still might have problems with L3/4 down the line but the line will be much longer.
Let me also tell you I've got absolutely no medical expertise and I'm speaking only as a patient and forum reader. You must do what you feel is best for only you will live with the benefits/consequences.
Dale