Double check your penalty on speed when carrying the rack. It isn't as bad as many think. Oh and you're not crazy, the 109's don't suffer from the added "weight" or drag of the rack in terms of maneuverability.
Double checked as You have suggested.
The DT rack weights 50lbs, the bombrack weights 110lbs. I still dont know where i stated that the 109 suffers from noticable maneuverability by the weight of the rack tho... Anyway, 50lbs is about 0.7% extra weight what practically noone can feel in a turnfight. Just as i stated before. The 110lbs is about 1.7%, what can be noticed in a synthetic duel situation, against very equal sticks. But this thread is about the DT racks.
So:
109F clean, 100% fuel, 200 rounds in the 20mm cannon, wep speed at 10-20 feet altitude: 332mph
109F, DT dropped, rack on, wep speed: 327mph The difference is 5mph.
109G6, 100% fuel, one cannon with 200 rounds, wep speed at 20 feet: 336
109G6, DT dropped: 331mph The difference is 5mph.
109G6, bomb dropped: 329mph The difference is 7mph.
109K4, clean, 100% fuel, wep speed at 20 feet: 367mph
109K4, DT dropped: 361mph Thats a 6mph difference, guessing i wasnt that far from the truth.