Haven't hunted with them (yet) but I have done a lot of loading and testing of these slugs.
Out of a smooth bore I have them shooting about 4" @ 50yds with 5 shot groups moving just shy of 1400fps (factory slugs advertised at "1600fps" chrony ~1450fps for me)
Putting 20ga nitro cards under the slug inside the wad practically cut my groups in half at any range.
My current favourite load is:
Remington high brass hulls
CCI 209M primers
40gr Bluedot
Claybuster clone of WAA12R wad
2x .125" 20ga nitro cards under the slug
6-point star crimp
Using only 1 nitro card groups about 6", no nitro cards in a WAA12 wad was grouping 7-8" (all at 50yds).
These are the Lee key-drive 1oz slugs.
I haven't tried them in my rifled barrel yet but have it on my to-do list. My parents property outside Sudbury allows rifle hunting so it's not a priority for me this season.
As for cost:
$0.04 - primer (1000 @ $37.99)
$0.23 - powder (40gr Bluedot @ $34.99/lbs)
$0.05 - wad (250 @ $11.99)
$0.02 - 2x 20ga nitro cards (1000 @ $8.50)
$0.00 - hulls (collected once fired hulls from friends who shoot buckshot and slugs for fun but don't reload)
$0.00 - lead (using up my free reserves; will have to buy some soon)
------
$0.34 - with free lead
If you have to pay for lead:
$0.14 - lead (1oz @ $50/25lbs)
------
$0.48 - buying lead shot to melt
Of course those prices don't take electricity cost, equipment cost, or your time into account as those vary quite a bit. You also may be able to get lead for $1/lbs instead of the $2/lbs I'm paying if you can find a local supplier. That would bring the slugs down to $0.41 each paying for lead. Cheapest I've found 1oz factory foster slugs is about $0.75 each (the Winchester boxes of 10). If these prove able to stay under 6-7" @ 100yds in my rifled barrel I wont be forking out $3 each for sabot slugs anymore.