So, here's my experience as it relates to the original question - Arce or WiiM Pro+.
I've had the WiiM Pro+ since it was first released. It is very good value for the money as a streamer/DAC device for someone just getting started in streaming and maybe doesn't have a very resolving system. The implementation of the AKM chip made for a pretty good-sounding device through my Onkyo AVR and a pair of vintage Klipsch speakers.
Sometime later, I upgraded my 2-channel music system to a Musical Fidelity M2si integrated amp. Everything sounded even better. Next came a Denafrips Enyo 15th DAC to take over DAC duties from the Pro+. I was still using the Pro+ as a streamer (Roon endpoint) but was using the Enyo as the DAC. That was a big improvement.
The Klipsch KG 3.5s (1996) were sounding better than they had in years but I was still wondering if it could be better. They are 28-year-old speakers after all. I ended up buying a pair of Zu Audio DW6 Superflys. The new speakers made a big positive difference.
Ok, so at this point it is Roon feeding the Wiim Pro+, feeding the Enyo 15th DAC, feeding the Musical Instruments M2si integrated amp, feeding the Zu Audio DW6 Superfly speakers. Things are sounding pretty damn good. Could the WiiM be the week link now? Are bits just bits?
A couple of weeks ago, I replaced the WiiM Pro+ with the Denafrips Arce using the I2s connection feeding the Denafrips Enyo 15th. Wow, the improvement was not subtle! Primarily, the soundstage got much bigger in all directions and the mids and bass became much fuller. The bass also exhibits so much more texture now. The timing and rhythm is noticeably better, especially on complex tracks where everyone is playing full-tilt.
So, for me, the Arce is a night and day improvement as a streamer over the WiiM Pro+. Of course, you would expect it to be. It costs almost 5 times more money.
Keep in mind though that I use Qobuz through Roon to stream my music so I'm not too concerned about Arce not having as robust a list of supported apps. I also already had a DAC that has an I2s input (and it is a Denafrips).
If you are using Roon and have a DAC with an I2s input, I wouldn't hesitate to try the Arce if you can swing the price. It's still less expensive than the PS Audio Air Lens, the Magna Mano Mk3.5, and the new Volumio Rivo+, all I2s capable streamers.
I hope this helps.