Reliability of SMD Components vs. THT Components

You are changing to SMD...
Why?

Unless there is a good reason, I wouldn't do it. The reason may be cost, time, size etc.
We I recently re-layed one of our boards as surface mount....it never made it into production.
The numbers just didn't add up unless the batch size became huge.
You also lose a lot of flexibility and repairability.
Maybe I'm a bit of a Ludite...

I am also suspicious of reliability since the change to lead free solder (I prefer the stuff that actually melts)
Del

I wonder if the new solder won't create more defective products thereby increasing the flow of waste materials into the landfills

We started change to SMT over 15 years ago. For a short time we had minor issues as we adjusted to the new parts. Certain "tweaks" were required on the design of PCB solder pads and in our solder process. End results were well worth the effort for our products. PC boards were much smaller with significant board and parts cost savings. All our SMT converted and new circuit designs performed better and were more reliable.