Thats really interesting WZ.
According to SFB, early romulans, of course, had the power and speed deficiency, and so bought and adapted several klingon hulls. To have SFC tell it, it seemed as if their entire fleet was practically replaced with Klingon hulls. D7s, Kilnk BoP FFs and DDs, etc. It was later, according to SFB, that romulans came up with their own tactical-warp capable late-era fleet.
To be honest, this always felt like such a cop-out to me. It makes sense that the Romulans would buy some klingon hulls, sure, but that many? Naw, I don't believe it. The devilhawk works perfectly as a second-generation BoP, something that didn't lack [insert Warp Drive or Anti-matter Reactors, which ever mythos you go with] but didnt come from the klingons. This later led into the third-generation Killerhawk, and Firehawk classes.