Regarding the Formula 603's.
Bunk, Defiantly provide your feedback to PJ.
I am a finger style 4 string player and I prefer lower tension strings. So as Bunk said these do work very well for me.
Those who know me from the beginning of coming on to Talkbass, I have spent over $600 on trying every brand of Steel strings out there.

At one point I was Donny's personal string supplier.
I despise the original version of exposed core Spector Steel Strings.
I can't play nickel but when I played regular Spector Nickels on other Spectors I felt the tension was too tight for me.
These Formula 603 strings I would say are not the string to use if you are tuning down.
Bunk, just curious the previous strings you have used,
Are the B and E string Tapered? If so, are they less or more tapered?
I personally dislike the feel of tapered strings and any tapered string I have used the string rattles "yes I adjusted the saddles up"
It just seems my attack doesn't match with a tapered string.
Remember the 4 string set is with a non tapered E string.
The 5 string set has a tapered E and B string. Reason: PJ wanted to make sure they fit in any of the tighter Euro & Korean 5 & 6 string bridges.
Worldeeeter,
Do you use LaBella Steels? If so, the Formula 603's will be much lower tension then those.