Instead of "butchering" an RB14/18 we are having a two port PCI riser built that recieves power from an external connector OR from the host PCI.
I would hardly call it "butchering", unless the person actually
is a butcher, and is taking his first attempt at soldering...
Replacing a 3 pin regulator is extremely simple, and it can be made even easier if you don't need to completely preserve the original removed part. This is by simply cutting the three legs of the part with small cutters, and applying a small amount of solder to the back edge of the part, on the small part of it's exposed heatsink with a high wattage soldering iron. As soon as the heatsink (which is also how the unit is mounted to the board, by solder) gets hot enough to melt the solder, the part will simply slide right off of the board, leaving a new-looking clear area for your new part, after briefly touching the area up with your iron....
The three different wattage versions of the regulator are definitely drop-in replacements for each other(while taking heat dissipation into consideration), and this is pretty much stated by the manufacturer in the fourth paragraph of the part's technical documentation:
http://www.national.com/ds/LM/LM1086.pdf
I've some interest in 2 slot PCI risers, and have tried tranquilPC and also Travla ones, both are "active" as they buffer clocks and a few other things, and have some jumpers. Some PC-builders report problems with passive 2-slot risers, guess it's mostly motherboard/PCI card timing. Mostly the problems are when running the bus at high utilisation.
The so-called "passive" and "active" risers you refer to usually work by rotatiing the IRQ signals for the alternate slot. While this may work for some cards, other cards will not accept this for multiple possible reasons. Since the second slot in the "passive" dual riser card, in essence, "wires itself" as one of the other PCI slots in the motherboard, you would also have a conflict if you happened to plug a card into one of the motherboard's slots that was wired parallel to your riser adapter's second PCI slot. The added length of the circuit board's traces are also an issue for timing, as you noted, even in the presence of simple buffering. A real "active" riser will use a bridge, or "arbiter" chip, which is basically a second PCI bus controller, cascaded on top of your motherboard's existing PCI bridge through one of your PCI slots. It will intelligently manage your additional PCI devices, and actually assign them separate logical locations in the system from your motherboard's other PCI slots. The bridge chips are not expensive in production(the majority of the cost for complex circuits with low parts counts is in the fabrication of the PCB, and not in the parts, unless one or more of the parts are rare or specialized), and some of them only cost a few dollars. If one were to get a circuit board produced for PCI expansion, surely it would be worth the few dollars(euros?) for the proper implementation...
Hitek