On the whole I would have to agree in basis that Rom tech did finally overshadow Klingon...But then, only to an extent. They're Warbirds were markedly slower than Klingon or Fed ships. likely due to their size. They are an enormous vessel. Their main drive/power source is something more advanced than anything even the Federation fields, but, also again, it obviously had its sorting out flaws as well...such as shattering the temporal scape of the universe...
Romulan vessels are not seen being detected through their cloaks as often or without great pains to do so, as opposed to Klingon vessels, but, once again...Romulan cloaks will not allow for transporter operation and we had proof ias early as ST:IV that Klingon cloaks DID allow for transports while cloaked. Also on the Reunification Episodes [TNG] and in the 2nd season old Klingons ep in DS9.
While their tech itself is more advanced, I don't think they are very far ahead of the field in how they implement their equipment.
--thu guv