This is just what I am doing but maybe it will help you. I have 4 hydra 26's and I will be switching to 3 xr15's blue once I save enough. I use the hybrid T5 also. The hydras have a lot of extra spectrums I personally dont use so I dont get the full potential or watts as I cut out most the whites and reds and greens. The new Hydras are the same way and they also use white lights for the moonlights, which I hate. This is all just my opinion. I guess you should decide what spectrums are most important to you. The xr15 has 50 LED's the hydra has 32. the Blues have mainly blue LEDs and you still get some of the other spectrums, just not overwhelmingly like the hydras are for me. It's just a waste for me to keep the hydras.