I just came off a shoot using the GVM 650 and 300w fixtures... I think they're bi-color, but my intention was to balance with sunlight, so I went their daylight setting all day.
I'm not sure if I heard the fans kick in at all, and was often working at ~70%. I'll have to check this again to be certain.
Really well constructed lights, some nice features like an included superclamp with ballast attachment (on the 650) so you can sit the ballast on a stand column and not rely on another clamp. There's a phone app but I didn't even bother to dive in yet, the UI on the light was already pretty straight forward. The 300 has a receiver for its power brick built into the yoke, something that might be common on constants but I geeked out a bit on.
They also both include a Bowens reflector - my Godox VL series lights do, too, so I guess this is common practice on mid range to higher endCOB/monolight style LEDs.
I intend to be shooting a lot more with constants in the coming year and I think these GVM lights hit a nice sweet spot of cost+features. For reference, these are the two units I used:
https://www.bhphotovideo.com/c/product/1774306-REG/gvm_gvm_pro_sd650b_bi_color_cob_led_video.html
https://www.bhphotovideo.com/c/product/1766628-REG/gvm_pro_sd300b_bi_color_spoltlight.html
I paid about $300 for my Nanlite FS300 when it went on steep sale a few years ago, and the GVM is, I think, a much better light for nearly the same price. The FS300 has been wonderful already, so I'm really happy for anything that matches or betters it.
Once the images go to print I'll circle back with some examples. I'd brought my strobe kit, but it sat in the car the entire time, the GVM's performed wonderfully.