Have you had REGS and SR: LOTD guides installed together for a full playthrough? Did it just require a few CR patches, like the REGS guide indicates? And did it remain stable throughout the playthrough?
I wouldn't mind trying my hand and at least adding pieces of REGS to my SR: LOTD install, but curious to hear about other's experiences with both.
I use most but not all of LOTD so I'm not sure how much of REGS can be added to a full LOTD build without adding too much VRAM or script loading. If there are questions about adding particular mods in the REGS guide I can try to help. The REGS guide mentions some of the main potential issues that I am aware of, but without some reports from users who are trying this it is hard to provide additional specific guidance.
I had some FPS problems with my game with the previous graphics card being used, but with the newer graphics card installed recently there haven't been many such problems. i don't think this is primarily due to the REGS mods; the LOTD mods being used certainly had a large effect on the FPS rate.