Is Roon Nucleus the best choice for Roon Core and as server?

I am in the market for a Roon Core and a server for my stored music Including high res, cd quality and some old MP3 I cannot find elsewhere. Some servers I have looked at suggest keeping the Roon Core separate due to the heavy volume of metadata. As I don’t have that much stored music, I would prefer to do these two functions in one unit and spend more on the streamer and the DAC. Is Nucleus by Roon the best choice? I see an RS9 being advertised but can’t find any information in it.
I have been using a Roon Nucleus as a server/streamer since November and am very happy with it. It has a bay where you can install an SSD or HDD.  I'd go with an SSD.  You can also just hook up an external storage device via USB.  Connect it via ethernet cable to your network and connect up your DAC of choice via USB (or for that matter via HDMI should you have that option) and away you go.  I have mine hooked up to a Chord Qutest via Curious USB Cable and am very happy with that arrangement.
Not a large collection of stored music.  Where the album is available on Qobuz, I am usually pleased to stream it.   Prefer to keep this purchase in the neighborhood of the Nucleus to spend more, as I said, on the other components.  Thanks for these suggestions, I will check them out,
If you can follow instructions you can assemble your own dedicated ROCK server. Mine cost about $600 not counting the price of Roon. The OS is free.

If you use Roons OS you don’t need a streamer just an endpoint. Some DACs can be endpoints if the DAC you like isn’t all you need is a Roon bridge.

In my system I have a NUC running ROCK connected by ethernet in my home office. My ripped music files are on a drive connected to the NUC. In my listening room I have a raspberry pi4 running Ropiee which is a bridge connected by USB to my DAC. I control it with Roon app on tablet.
I built a Roon Rock server referenced to the top spec Roon details on their webpage;
Intel i7 8th Gen NUC
256GB SSD for the free "ROCK" OS
1TB SSD for content;
Cost about $750 all in; 

It's my understanding the above build is identical (save the awesome fanless CNC case of Nucleus) to the Nucleus +;

Best audio and functional performance I have heard yet from Roon. Boots in less than 3 seconds; Stable 24/7; Zero glitches, hangs, snags, pops, etc;
I messed around with Roon running in several popular platforms over a long period of time; I spent a lot of money experimenting with Roon and these various hardware bits; It was a mixture of fun and frustration, but the first hand experience was worth it; 
I highly recommend to anyone--build a Rock based Roon server; Go for the top spec; It's worth every penny!!