My top speed in my sprints is down about 20% compared to when I was 30. I wasn't as smart back then so I couldn't translate my much better sprint speeds into better results. Other than that I really don't have a good metric. I don't train hard enough to see if I can TT, I don't train in the same area as before so I can't relate general gearing trends etc.
My best ever 40k TT was a 1:01:30. My second best was about 1:03, on the same course. My best 7 mile TT (local club TT) on basically the same TT bike (disc, 24" front wheel 17mm rim/tire, 100k bars, etc) + skinsuit + TT helmet was a 16:28. The course record was 14:05.
I could never climb, still can't. I raced at weights ranging from 103 lbs to 210-ish lbs. I've never finished a RR in the group (Juniors or Cat 3s), I've never made it past the RR in a stage race (always eliminated on time, Juniors or Cat 3s).
w/kg is critical when climbing. It's less important (but still nice to have a good ratio) when dealing with flatter races.
I sometimes placed as a 3, whatever the year/age - my best was a 2nd in the summer a few times. I could win a training race. I upgraded to Cat 3 in 1986 when I started racing Senior.
I only ever qualified to upgrade to Cat 2 in 2010. My w/kg was 3.1 w/kg (70 kg / 155 lbs, 220w FTP). I sniped crits to get my upgrade points. Currently I'm 2.85 w/kg range. This year, on 61 total hours of riding so far, I've won 2 (uphill) field sprints in 8 races, got shelled in one.
I tend to race the 3s, they're (significantly) easier than the M35+. M45 is better but I have teammates who are younger than 45 and typically I prefer to race with them than with zero or one teammate.
If I had a 250w FTP or a 3.0 w/kg ratio I'd be stronger than I am now. In 2010 I felt untouchable, relatively speaking.