As an alternative to dropping the Infidel, what about increasing the cross-bleed of escorts? Say, something more like 0-6 Imperial escorts per 500 points (rather than 750) or part thereof. Even if it's just an option, that might encourage people to build more rag-tag escort squadrons out of a mix of Imperial and Chaos escorts. A combination of Cobras and Iconoclasts and Infidels could get you a torpedo squadron that could also throw a few punches too, for example (alternatively, the Iconoclasts could end up being used as ablative shields for the Cobras... not a bad idea and not necessarily overpowering either). There probably aren't too many people (other than me) who'd be sorry to trade out their Idolators for Firestorms in an escort squadron either I suspect.
For that matter, what about adding the Recommissioned Escort from the Rogue Trader List? (the inverted Cobra, 1 torpedo, 2 guns).