The question with after market is always install quality.
Will they snap off or knock a big hole hitting an obstruction?
If you hit something with enough force to snap off a stabilizer fin, the fin is probably not the biggest problem you'll have that day.
As others mentioned, install is key. The brand is only part of the equation. Undersized fins won't be effective except at higher speeds. Our Solo came to us with Wesmars installed, aftermarket. The install wasn't top notch. Luckily, the basics were sound- good design/application, fine structural integrity (our hulls are designed for stabilizers, some just don't have them installed OEM, but the structure is there nonetheless) - but the details of the install were lacking- wiring not tidy, hoses not routed the best, and most importantly, seals on the stbd fin shaft installed upside down. This allowed seawater into the shaft and it corroded and galled. Bad! I was able to free it and correct the damage without significant rework, but my buyer survey missed it, along with many other items. Another story. But all fixed.
I would not be without stabilizers. And NO,
YOU DO NOT HAVE TO DO 12 KTS. for them to be effective. That is patently incorrect. Ours work at 5 kts. The only time I've done 12 kts is leaving Montreal or on the East River! It's a function of the area of the fin, and integral to the design for the individual boat, not one size fits all, by any stretch!
Maintenance- I've re-sealed the shafts on 5-6 yr intervals, it's a day's job, I DIY and need a hand to re-insert the fins, although I've done it solo. The seals are COTS Parker-Hannifin hydraulic cylinder seals, Wesmar sells them for 5X $, there is also an O-ring seal, also COTS at hydraulic supply house. A fiberglass sleeve bearing, maybe req'd every other service is OEM, not cheap, tricky to R&R, a dry ice bath helps install.
Drag/performance loss- who cares? It's so minimal. The difference in on/off is literally stuff flying off shelves. If you do big water, stabilizers are a godsend. Even ICW cruising is enhanced with the difference they make in handling the wakes of those wonderful sportfish delivery jocks.
If your new-to-you boat came with stabilizers installed, thank the installing owner, they did you a huge favor!