ive never driven an 80 but as you know ive got a 100 and my mrs has a 1.6 16v dynamique
ragging about flat out redlining everywhere the 1.6 16v is faster (just) untill about 70/80mph
the dci100 has so much overtaking torque for such a small car, diesels are never quick at accelerating but get the 100 into 3rd,4th and 5th and it pulls really hard.
my honest opinion would be ignore all these people that say the 100 has a "dodgey" box, take a test drive in one, your free to have a go in mine if you like take a good around town test drive to get used to the box, i drove mine and instantly thought no no no but 30 minutes later i loved the box.
standard for standard the 100 handled slightly better than the 1.6 16v, you can feel the bit more weight over the steering. think it has slightly thicker ARB's too