Looking at a bike form the mid 90s with 105 STI (first year for 105 STI I believe). Any comments or general consensus about reliability of older STI or ergopower?

How would a mid to late 90s mid-tier group (105/daytona) performance compare to newer low-end such as Tiagra, Sora and Mirage?

Also thinking of upgrading my current bike (1979 Schwinn Super Le Tour) with some mid 90s 105 (STI as well) because I can get my hands on some parts fairly cheap (<$100 for STI, brakes and derailleurs. My reason is not having to reach for downtube shifters while riding in winter weather. Is there any reason against this route?

Otherwise, my other path would be to start gathering components and eventually get a good deal on a used titanium frame to build an all-purpose bike as opposed to having multiple bikes.

Edit: They actually appear to be from the 2nd year 105 went to STI. I don't know if that makes any difference.