I’ve used Melodyne Studio, VocAlign Pro, and RePitch pretty regularly, without any recent problems. I should note that most of that work was in Cubase 13 as I was finishing up an EP remix project when Cubase 14 came out, and I’ve only recently (since Cubase 14.0.10) gotten back to more Cubase use, and I’m not sure I’ve yet gotten to parts of my workflow where I’d use those three plugins on my recent projects.
I have also recently tried SpectraLayers Pro 11 with ARA for unmixing a song to help me make a chart. It really took over my computer (I’m talking all CPUs pretty nearly maxed out) and took a while, but it did work.
The only crash-type problem I did have was with WaveLab Pro 12, specifically when trying the “make extension permanent” way of rendering (see Cubase 14.0.10 crash attempting to make WaveLab 12 ARA extension permanent). I ended up having to work around that by bouncing the clips (which is my normal practice for uses of the three plugins I use the most anyway, but something I was hoping to delay a bit in the context where I was using WaveLab).
My computer is definitely not state-of-the-art, with the basic build being 10 years old, including the ASUS X-99 Deluxe motherboard, Intel i7 5820k CPU, and 16 GB RAM. I have upgraded it over the years, replacing hard disks with SSDs for the elements that matter to Cubase, and more recently replacing my video card, albeit with one that is still fairly dated (my son gave me his old one when he upgraded) and not applicable to use in some modern contexts such as SpectraLayers’ potential for speeding some of the processing up by processing it on the GPU.
Further back, I have had a few crashes with ARA uses of RePitch (which was likely quite new at the time) and some earlier versions of VocAlign (but those were very rare).