it could be that the Medusa has an obscene amount of spare OP though.
If you take the four frontline destroyers without any skills increasing ordnance points, assume that small mount weapons consume 5 OP, medium mount weapons consume 10 OP, and large mount weapons consume 20 OP, then the Medusa has 35 OP left over after filling all its weapon mounts while the Enforcer, Sunder, and Hammerhead each have 30 OP left over. From Computer Systems, Mechanical Engineering, and Technology Aptitude, a Medusa can gain up to 27 OP, an Enforcer can gain up to 30 OP, a Sunder can gain up to 28 OP, and a Hammerhead can gain up to 24 OP; under the above assumptions about the armament, that would leave the Medusa with 62 spare OP, the Enforcer with 60, the Sunder with 58, and the Hammerhead with 54. From Optimized Assembly (Ordnance Expertise 10), a Medusa can gain up to 11 OP, an Enforcer can gain 14 OP, a Sunder can gain 13 OP, and a Hammerhead can gain 10 OP. Assuming that Optimized Assembly is the only OP bonus in effect, a Medusa would have 46 spare OP, an Enforcer would have 44, a Sunder would have 43, and a Hammerhead would have 40; if both Optimized Assembly and the full OP bonus from Technology Aptitude, Mechanical Engineering, and Computer Systems are in play, then this would leave the Medusa with 73 spare OP, the Enforcer with 74, the Sunder with 71, and the Hammerhead with 64.
Without looking at specific variants of the ships, then, it would appear as though the Medusa does not have a significant advantage in OP over the other combat destroyers under any set of skills you choose; only the Hammerhead lags behind to any significant degree. I certainly wouldn't say from these numbers that the Medusa has anything like an 'obscene' amount of spare OP, at least not by comparison with the other frontline combat destroyers.
If, as suggested, the Hammerhead is given an additional 5 OP, then under the above set of assumptions about the cost of the armament, a fully-armed Hammerhead with no skill bonuses has 35 spare OP (same as the Medusa, 5 more than the Enforcer or Sunder), 45 with Optimized Assembly only, 60 with Tech 10 + ME 10 + CS 10 but no Optimized Assembly, or 70 with both Optimized Assembly and full OP bonuses.
Regarding the comments about the Venture:
I don't really see any good reason to improve it. For a "civilian" ship, it's already quite well armed (armament is roughly equivalent to that of the Falcon, and then you get to add in a flight deck on top of that) and extraordinarily resilient (between a shield generator which, at 1 flux/damage, is fairly efficient for a low-tech ship, a rather deep flux pool for a ship with only 3 flux-generating weapons, and the second-best hull strength and armor rating of any cruiser, a Venture can take quite a beating). On top of that, it has the greatest cargo capacity of any cruiser (though the Apogee and Starliner are close seconds, at 450 to the Venture's 500), it's tied for greatest fuel capacity among cruisers with the Apogee (300 each; Starliner at 250 is the only real second-place option due to the Dominator's higher fuel consumption), and it's a more efficient freighter in cargo*ly/fuel
1 than any of the destroyer-scale freighters or any other cruiser (167 cargo*ly/fuel for the Venture as compared to 150 cargo*ly/fuel for the most efficient cruisers and destroyer-scale freighters).
The Venture may not have any one outstanding aspect, but it's a reasonably good all-around ship whose only major weaknesses are its civilian-grade hull, its reliance on missiles and its relatively low speed.
1I care far more about cargo*ly/fuel than I do about cargo*months/supply when looking at freighter efficiency. Burn speeds appear to have changed so that a ship moves at 0.1*(burn level) light years per day, so a Venture moving at rated speed in hyperspace is consuming 0.7*3 = 2.1 fuel per day, as opposed to just 15/30 = 0.5 supplies per day when not recovering CR; unless my activities lead me to spend considerably more time idle or in system than in hyperspace, or unless supplies are considerably more expensive than fuel, the greater part of the travel expenses for my fleet's freighters are going to come from fuel costs.