Well, let's see what we're looking at...
Fiocchi High Velocity 12HV00BK, 12 Gauge, 2 3/4", 9 Pellets, 1325 fps, #00 Buck Nickle Plated Lead Shot, 10 Rd/bx $5.28 box/10+boxes $5.02
Remington Buckshot SP12 00BK, 12 Gauge, 2 3/4\", 9 Pellets, 1325 fps, #00 Lead Buck Shot, 5 Rd/bx $4.16 box/10+boxes $3.95
I don't know if anything has changed with recent lot numbers of either load. I have some of the Fiocchi that's the same catalog number, the catalog number on the Remington I have handy is 12B00- I don't know if that's a different load than what Able lists, what I have is plain old 9 pellet 00 Express buckshot listed at 1325 fps.
IMHO there's no real difference in quality in the two. Fiocchi makes good ammo, as good as any manufacturer, and their 12HV00BK is one of my favorite non-premium loads. The Remington Express stuff isn't one of their premium offerings either. I would expect both to perform about the same out of the same guns, subject of course to all the vagaries that shotgun barrels induce in patterns made by different loads. I'd expect moderately sized patterns, in other words, in between the really cheap stuff like S&B or Rio Royal and the premium loads like Federal with FliteControl wads.
There are some differences. The Fiocchi has plated pellets- a plus in avoiding pellet deformation. The Remington has 'grex' or plastic buffering to pad the pellets- should be about a draw in that regard. Both have one piece plastic shot cup/wads. Both are star crimped, the Remington crimp is sealed with some sort of adhesive, the Fiocchi is not.
My advice would be to buy a relatively small amount of both, about 25 rounds or so. Shoot a few patterns with both at the maximum range you're likely to employ your shotgun, one pattern per paper or cardboard target. Then compare the patterns for size and even distribution.
Load the magazine of a standby tubular magazine shotgun full with alternating rounds of each brand and let it sit for as long as you usually go between shooting up the ammo in your HD gun and replacing it. Then check each round by manually inserting it in the chamber to make sure no cases have swelled or bulged under magazine spring pressure.
Lastly, run about 15 rounds of each load through your HD gun as fast as you can load it and shoot it. You want to make sure the ammo will run in the gun when the gun is hot, and that should do it.
The absolute critical thing in defensive ammo is reliability- the ammo has to run in your gun no matter what. If either fails the reliability standard, it's a no go. If you get essentially equal performance from both brands in all your tests, choose the less expensive brand and don't worry. If one brand seems to perform better in your particular gun, then choose that brand.
hth,
lpl