I think you're logic is really good. It's improved survival rate vs risk of permanent side effects. That's always a trade-off. And the final decision should always be the patient's. But I personally would always follow the doctors advice, or seek a second opinion. 
Your question "What is the 5 year survival rate compared with a separate 100 Stage 1B patients who choose not to have the SNB?" is an excellent one. But the doctor may not have a meaningful answer. All cancers are different. He may not want to give you statistics that may feel, to him, like comparing apples with pears. But if the doctor can give you an estimate of survivals rates (with or without SNB), for your own cancer, based on his expertise and experience, then that would be very useful. 
You could even ask him 'If you were in my shoes, would you have the SNB?" but medics are sometimes reluctant to answer questions like that.

 

Harry, I have gone round this and researched as much as I can.  As you allude to, there is no black/white on this, there are too many variables.  The net is, there is no statement forthcoming that survival rate is affected by SLNB.  I apply logic, not feelings, in these situations and my conclusion therefore is to not have it.  No known outcome benefit vs potential (if low) surgical risk.

Another example of my applied logic was when I had a Basal cancer removed from my back some years ago.  The diagnostic excision removed the Basal cancer.  This was then reviewed with the medical team, who stated there was no risk from Basal cancer other than it might grow back if not fully removed, and asked if I would like a second WLE.  I stated that I did not see the point - either they had removed the whole cancer (which has been the case) or if not, it would grow back and they could do a full WLE then.  The doctor said my logic was flawless, but that most patients chose to have the second WLE.  I see this as a waste of NHS money, performing clinically unnecessary surgery. Some my argue that it makes some patients 'feel better', but should tax payers cover this cost?  Using the 'feel better' logic, why not perform SLNB on Melanomas under 1mm?  (A cost benefit line has to be drawn - which is what NICE tries to achieve.)

Harry, I have gone round this and researched as much as I can.  As you allude to, there is no black/white on this, there are too many variables.  The net is, there is no statement forthcoming that survival rate is affected by SLNB.  I apply logic, not feelings, in these situations and my conclusion therefore is to not have it.  No known outcome benefit vs potential (if low) surgical risk.

Another example of my applied logic was when I had a Basal cancer removed from my back some years ago.  The diagnostic excision removed the Basal cancer.  This was then reviewed with the medical team, who stated there was no risk from Basal cancer other than it might grow back if not fully removed, and asked if I would like a second WLE.  I stated that I did not see the point - either they had removed the whole cancer (which has been the case) or if not, it would grow back and they could do a full WLE then.  The doctor said my logic was flawless, but that most patients chose to have the second WLE.  I see this as a waste of NHS money, performing clinically unnecessary surgery. Some my argue that it makes some patients 'feel better', but should tax payers cover this cost?  Using the 'feel better' logic, why not perform SLNB on Melanomas under 1mm?  (A cost benefit line has to be drawn - which is what NICE tries to achieve.)