I just found this thread. My story is long and has been repeated many times in this forum so I'll just cut to the chase. I had ridden my bike fast since I was a kid. When everyone had banana seat bikes, I had a five speed drop bar bike. While in college in Boston I started working at a neighborhood bike shop for extra coin. The guy hooked me up with a Koga Miyata frame and a full Ti SR group and I started riding at night after class. The shop regulars were not the brightest bulbs but they rode their bikes at night too, and we would do workouts together on the streets and on the Esplanade. One guy was a Cat2 and suggested that I try racing. I went to the now infamous Wells Ave. where at the time they had an A and B field. I bought my one day license and won. I came back the next week and lapped the field solo. At that point the club that ran the race handed me a skinsuit and bought my license. I upgraded to Cat3 the next year and Cat2 the following year. This was when there were no points, you were deemed ready to upgrade at the jurisdiction of the officials. If you were fast but could not handle your bike you did not upgrade. You had to qualify for Nationals back then, too. During my second season I was recruited to ride for one of the strongest amateur teams in the country that spawned three pros. The team didn't play nice together after a while, so another team handed me a bike and asked me to be the leader. I rode with them for two more years, until the grind of being a newly minted engineer and racing at the highest level without proper training took its toll and I burned out and quit. In 2010 I decided to get back on the bike so I bought a brand new modern machine and started riding. I joined this forum and asked the same question you did, should I return to racing. If you search around here, you'll find it. I decided to return as a Cat3 and earn my way back, which I did in less than a season.
I race both Masters, all age groups, and Cat2 and above. At 57 I can still top 20 in a P/1/2/3 race. I haven't done a P/1/2 in a while but most of the guys that finish ahead of me are not Cat3's. If you have raced before, not a lot has changed as far as the racing itself goes. If you want to succeed in criteriums you will need to train for criteriums. Same for road races and time trials. I am a criterium specialist. It's pretty much all I do, because I friggin love it.
Find your niche, train for it, and stick to the plan. Don't let the past guide you.