My 1983 Nishiki International is faster, more comfy and better looking than my 2007 Sirrus. I paid over $550 for the Sirrus and $50 for the Nishiki. I once rode the Sirrus 40 miles in a race and it was hell. I rode the Nishiki 25 miles this weekend and felt fresh after.
Don't count out 1980s rode bikes, they were and are great. My Nishiki doesn't have any plastic parts on it and the rims don't go out of true with every pothole like the Sirrus.
Bottom line is, if you want to join the 21 century, skip the Sirrus and get a modern rode bike like a Carbon fiber bike with brifters and at least Tiagra. You will spend $1500 plus but it is better than $500 on something like the Sirrus when that is not what you really want.
Or, and this is probably the best option, update and tune up your old bike. Maybe you need to do simple things like grease the moving parts and get new tires and true the rims. You would be surprised what a big difference things like that make. I bet I could have your old bike ridiing better than any Sirrus ever could.