Hey now, lengthy posts are my territory!
Seymour pickups are custom shop only and have a few options of the type of sound you want , and humbucker or single. As far as I know, they are direct replacement, and some people who have them love them. Untill the RIC toaster went up to 150 bucks, I thought the SDs were a bit pricey, but now seem comparable. I have never heard or seen one in person to give you anymore info. I am sure someone here will chime in on their experiences.
I believe they(RIC) offered a piezo bridge on their discontinued Laguna, but it was a bolt to the face of the guitar type deal and not the "R" tailpiece and bridge combo. I have no idea how they sounded.
The HB-1 split,IMHO,was not to my liking, and didn't brighten up the sound like other humbuckers do when split. In regular mode, I didn't like the sound in both the bridge and/or neck positions of my 330FG. I was hoping for a higher output toaster sound with no 60 cycle hum and a little oomph to give the bridge a little more krrang, but not at all in that ballpark. I threw it in the neck thinking I could roll the tone back for a good "Cream" style woman tone, but no dice there either. Some folks here put them on their 330s and love them, but they weren't quite giving me the sound I was looking for.I understand they sound great on the solidbody guitars, and wicked on the basses.
There has been a lot of discussion on the RIC forum lately about folks wanting pickups that are reverse wound so you could buck the hum with both on. Many in depth opinions/arguments/wishes that you can go there to read about.
The higain pickups that came on my guitar originally sounded muddy, and apparantly it is a popular opinion of ones made in the mid 2000s before these new adjustable pole piece high gains came out. I have one of the new ones in the bridge of my 4003AFG(this pickup kicks serious butt ), and replaced the neck with a toaster for the best of both worlds.
These new high gains are really supposed to be the bomb as they are described as having the clarity and brightness of a toaster, and the power and bite/growl of a high gain. I am planning on getting one of these new hi gains for the bridge position of my 330, as the toaster is great there, but if I can get a little more cash register ring out of my 330(think "Modern World" album by The Jam)I would be a happy man.
There are some Asian copies out there that fly under thr RIC radar you see from time to time, but they are slightly bigger and sound like overly microphonic ****(IMHO).Don't waste your money on those.GFS had some toaster copies they made untill RIC legal shut that down(legally their right.)
Companies are not willing to make aftermarket parts if there is even a chance RIC will put the legal boot down on it. This, combined with the fact that all of the major harware(pickups,tailpieces,bridges etc) are completely different in both size and design, make offerering aftermarket parts for these instruments a rarity. RIC is a great company that has managed to do a very good job of protecting it's copyrights, but some, if not many, feel they take things a little too far sometimes.
So, in a nutshell, you get what you get, a top quality handmade American instrument that can give you a lifetime of joy and pleasure. You can contact Sergio on this site about modifying your existing pickups as he is highly regarded for his expertise in these matters.
Whatever you do, please don't hack up your guitar to fit full size humbuckers, aside from all of the "taboo no nos" you'll hear, you will drastically reduce the value of your instrument. I had a guy come in to a shop I worked at years ago with a 330fg someone had put a Dimarzio Super Distortion full size humbucker in the bridge, and it was a sorry looking guitar. It was like "What's this, the Ace Frehley Signature model?" Really was a shame.
Good luck, and hope this helped you out.