Sounds familiar to me, though not the 5W/kg… I’m sniffing around 327W at 77kg (4.25W/kg).
I started racing some local crits this summer and learnt a lot. I learnt I could hang with the Cat 3s until the last corner when half the field would come past me. Even the Cat 4s I really struggled to hold on the sprints.
I’ve spoken with a few coaches on this and it’s been helpful. Essentially the type of riding I’m doing, i.e. the crits, and even the specific track, 4x90deg bends and 2xhairpins, sprint power is more important than FTP.
So I’ve been putting in 10s standing start sprints and 10s sign-post sprints outside at the weekend. Mixed with this I’ve been swinging a 24kg kettlebell 3-4 times a week for 20 reps at a time.
Also another great workout is 6s seated sprint 24s recovery. 20 reps, 5 mins recovery then another 20 reps. A short but intense session.
On Friday I threw in a little sprint against a friend and hit a new max of 1309W 1s peak, 1213W 5s peak. Keen to get my peak power up 1,400W so a bit of a way to go, but I’m sure I can do it.
In terms of what’s right for you, I’d say that depends on what type of events you want to be good at, but at 5W/kg I’d imagine you can hold in with a really strong group for a long time, but you’ll never win the race.
I’d suggest going into FTP maintenance whilst putting some time into 5s-5min power.