My experience with Hipersonic2:

I got Hippersonic 2 very recently. Don't be surprised, I'm almost always late when it comes to music technologi, and go rather cheap for my own convenience!
Hipersonic can be purchased for about 25€, which is not bad at all.
Ok, it sounds very old school, but in my opinion, there are interesting acoustic drum patches, 808 samples, and other stuff that can be resampled and reused so that noone ever would realize you are using such old stuff. Just be creative and never tell specially the people who are very picky about gear and software, that you payed 25€ for an instrument library. Otherwise, although your music may sound amasing, they will probably underestimate it! KKK!
Now, I will share with you my experience with Hipersonic and describe its configuration and use in Reaper.
We can install Hipersonic just like any other VST plugin, pressing next in every option. Then, just tell Reaper you have a new VST in your collection, with the propper scanning feature, and there you go.
However, to use this Steinberg multi-instrument library more easily, it is also necessary to install the JS plugin called BSmart.
To do so, just pick the plugin, and copy its contents to the directory
User\appdata\roaming\reaper\effects.
And boom! Reaper, Hipersonic and the add-on are ready to work togeter!

Settings:

Step 1: Insert Hipersonic as a VST instrument on a track. Keep in mind that to avoid the bridge window, before loading Hipersonic to the track, with your cursor on it, press the applications key and down arrow until run as submenu. Go in there and choose the Embed Bridge UI option, and press enter. That way, the bridge window doesn't bother again.
Step 2: Insert the BSmart JS add-on as a normal effect.
Step 3: Make sure the JS add-on is at the top of the list in the effects chain.

Use:

With the two elements placed on the track, we set cursor on top of the BSmart and control the various banks, patches and their configurations with the BSmart. It's easy, the tab key and arrows do it all!

Trick:

This library is very lightweight. Thus, we can either load multiple instances, for example one per track, or we can send multiple tracks with different instruments to just one instance of Hipersonic. To do this, follow next steps:
Step 1: Create a track and insert only one instance of Hipersonic. The next tracks will be those with the instruments.
Step 2: Create as many tracks as necessary, within these conditions:
A: All tracks further down the Hipersonic track must have a send set to the Hipersonic track. This setting is configured in the context menu using the alt key and the applications key, scrolling through the options with the vertical arrows and confirming with enter.
B: All tracks further down the Hipersonic track must also be midi tracks, directed towards the controller keyboard in use, and the controller must be configured for all channels.
This is configured in the context menu using the applications key, imput submenu, Midi option, scrolling through the options with the vertical arrows and confirming with enter.
C: Each of the tracks down the Hipersonic track must have the input routed to the corresponding Hipersonic midi channel.
For example, if we want the drum track to enter channel 1 of hypersonic, we rout it to channel 1. If we want the bass track to enter channel 2, we rout it to channel 2, and so on.
This routing is done in the Imput Midi submenu, entering Map Imput to channel, within the context menu using the applications key, scrolling through the options with the arrows and confirming with enter.
D: All tracks down the Hipersonic track must have an instance of the BSmart controller, and this must have the midi channel set to the desired input. For example, if the drum track is going into channel 1 of Hipersonic, the midi channel parameter in BSmart should be set to channel 1.
If the bass track enters channel 2 of Hipersonic, the midi channel parameter in BSmart must be set to channel 2, and so on.
The instruments of each track and their parameters are configured in BSmart.
This is done in the BSmart options of each of the tracks, tabbing across the parameters, and choosing the options with the vertical arrows.
This way, we can send multiple instrument tracks to a single instance of Hipersonic, up to a total of 16 tracks per instance, which is more than one would normally want.
For eas of use, we can even configure Reaper to arm a track and monitor it individually when it gains focus, disarming those that are not. Want more?!