Seth Lover's verses Alnico II?
Seths are generally cleaner and clearer than A2Ps, in no small part because they are a bit lower in output. This especially holds true when comparing the two neck models to each other. They are very notably different sounding pickups. The A2P neck is noticeably hotter and muddier than the Seth neck (though not muddy in the grand scheme of things).
The two bridge models are closer in tone. IME, the A2P bridge seems a little hotter (in terms of output), yet brighter than the Seth bridge. The Seth is a little bit warmer and quieter - more "laid back."
I would say that the A2P bridge is a very good "poor man's" alternative to the Seth bridge. They're not too far from each other. However, I wouldn't try to replace the Seth neck with a cheaper alternative. There is no other Duncan pickup that does what it does nearly as well as it does.
I would go for a used Seth set myself. That way you'd get the Seths, but below the price of brand new A2Ps.