This forum, well, and several others, really dislike Neptune and the SKY lights. With that out of the way I think the one poster above,
@blaxsun, said it well such that you may not be able to judge as you have them mounted. Even if on, or off, at different times. Different LED layout, width, and your spectrum/intensity setting. It is going to be a challenge.
At this point it really is up to you what to do. Not sure if you have but any chance you make a list of pro, con, what you like, dislike, etc?
App control
Ease of use
Spectrum
Connectivity
Noise
Mounting
Spread
You didn't say what XR you bought pro or the base unit but that could also factor into the decision. I've not owned the XR's so really can't say so trying to remove any bias I may have. My initial take is you would spend less buying 1 XR vs 2 SKY's. Flip side is the XR's are more expensive than the SKY's. If you sold the XR's you may be able to recoup some money and it may be moot. Then again you will probably also recoup by selling the SKY. Glass half full, empty - seem my point?
One thing that is nice about the SKY is that you can integrate it easy enough. Single app. Sort of important to me but I'm not you
Another nice feature is that the SKY has 14 different presets with the base light. XR's you have to choose standard, or blue and then dial in or use the pre-sets. SKY gives you a bit more spectrum control should you choose wrong (edit: my point here is they sell 1 kit that can support both sides of the spectrum without losing a lot of par). In short decent LED spectrum which allows the hobbyist to flip spectrums without loosing par. This is often overlooked and why some add two choices.
Honestly you can't go wrong with either kit. One may save you some money the other a nice quality of life improvement. Both will grow corals. 3 over that size tank will give you room to grow.
