Hi there
I have a fair number of Dust miniatures/vehicles and a small mountain of 28mm minis inc a large number of Pulp. Dust is 1/48, 28mm is vaguely 1/56 so IMHO the two don't sit well together as far as representing standard individuals is concerned, Dust minis will work with 28mm minis if you want to represent individuals of even more "heroic" proportions. The terrain and armoured walkers, battle-suits etc work fine with 28mm although some of the vehicles are gigantic. The planes should be fine.
Cheers, G-Donk