The difference between both versions is the kind of rectification. While the LS-HPULN uses Schottky diodes for rectification, the LSIB-HPULN uses MOSFET's controlled by the "Ideal Bridge" controller. The benefit is a very low voltage drop caused by only ~ 0,009 Ohm resistance, which causes a very small heat dissipation.
The picture shows the voltage drop after rectification (and before the regulators) for both versions. As can be seen, voltage drop is much smaller than with diodes, although low Vf Schottky diodes are used. Please take notice, that higher voltage can be a huge advantage, but causing too high voltage headroom by wrong transformer calculation can also be a disadvantage.
The LSIB-HPULN PS also has the possibility to use a snubber for reducing transformer ringing, which is absolutely recommended.
In case your order includes a transformer, the snubber will be configured to it. In case you order the LSIB-HPULN PS only, you need to configure the snubber (it's one resistor only) by yourself, or simlply don't publish the snubber.
Please take notice, that the "Ideal Bridge" controller needs >9VDC to work, your transformer should have also >9VAC or less only in case of low current need / low load to guarantee enough voltage under all circumstances.
Which output voltage is recommended?
This question should be answered individually. In case only few mA are needed there is no reason not to adjust 3V for example. The more current is needed, the less voltage difference between input and output voltage should be calculated to avoid unnecessary heat.
The LSIB-HPULN PS can be used with DC as well. 9VDC is also needed here to work, but there is nearly no voltage drop comparing to your source voltage (resistance of ~ 0,009 Ohm).
The picture shows real measurements with an MPAudio Audio Grade transformer with 100VA / 12VAC.