I did a few crits with a 2x6 DT shifter bike back in 2009. It wasn’t dangerous, but it did suck. That 1988 bike was absurdly outdated at the time but it’s been a very long 13 years in bike tech. The shifters are really the least of your worries. The idea of riding a floppy old bike with skinny 23mm tires and single-pivot brake calipers in a racing pack of today’s bikes… eeehhhhhh. It’s not confidence inspiring for anyone. Nowadays the broke youngsters racing outdated machines are on Lance-era aluminum with 9 or 10-speed STI and dual-pivot rim brakes. That’s basically the exact equivalent to what I was doing in 2009, but it’s a better balance in my opinion. I got started on 80’s bikes with SIS downtube shifters, so I totally relate and get the appeal. There’s a tactile sensation with a good set of DT shifters that’s really delightful in its way, and completely different from the feel of modern integrated shifters. It’s great to ride these bikes and fun to break them out for group rides in the right crowd. But for racing or competitive, fast group riding among modern bikes, no thanks. And as I said, not because of the shifting, there are other safety concerns that are much worse, primarily the brakes.