Guitar Fetish don't build their own pickups. Several of their models are identical to those offered by the Artec brand, so it seems likely that Artec are the OEM (as they are for Wilkinson, Tone Rider, Iron Gear, Giovanni, Warman and several other brands). To widen the net slightly you could simply find the corresponding Artec model to the pickup you fancy and see if anybody has reviewed that pickup. For example Artec build a Dimarzio X2N copy that is sold under various brand names (Crunchy Rails in GFS parlance). In general if a cheap pickup looks very similar to another cheap pickup then it is likely from the same OEM. The GFS Crunchy Rails pickup looks pretty identical to the Entwistle Pickups X3 model.
The only issue I can foresee is that because Guitar Fetish can buy in bulk they might specify differences in the pickup specs. For example they may request an overwound cream-coloured PAF-type humbucker with hex-bolt pole pieces. Visually this would look like an Iron Gear Steam Hammer humbucker (and the Dimarzio Super Distortion of course) but may sound different if GFS request a different magnet or output rating.
My biggest concern would be that Artec simply build one style of humbucker, and adjust one attribute without worrying about the others. When Seymour Duncan, Dimarzio, the boutique winders et al decide to build a hot humbucker they don't simply take their standard PAF humbucker flatwork and magnet set and stick a couple of thousand extra turns on each coil. They might have done this in the '70s (back in the bad old days when some guitarists took two original Gibson PAF pickups, stacked them vertically and wired them in series to get a hotter signal), but builders tend to consider ever element of a pickup when it comes to adjusting an element of the design. A cheaper builder will probably not do this, simply swap a magnet or set the winder to a different count number without due consideration for the impact this will have on the pickup's tone.
I would warn that cheaper pickups might be microphonic, but the most loyal PAF clones come without any wax potting, and authentic Strat pickups get a perfunctory dip in lacquer by way of potting. Some people claim the microphonics enhance the tone... but usually only when they've spent considerably more than GFS prices for their pickups.
