To me T5 only tanks look great in pictures but washed out in person. While the camera loves the uniform light distribution my eyes prefer the shadows and contrast created by other options. T5 and LED combinations offer a solution that makes sense in some ways but contradict most of the advantages I've come to appreciate with LEDs. Mixing T5s with LEDs introduces these problems to a fixture which was originally sold based on the fact they didn't have such problems. Then there's the control aspect that T5s just don't compare to. Yes you can dim T5s but it doesn't make it a good idea, dimming florescent bulbs is not the same as dimming LEDs and it never will be, if you've done this before you know.
I'd say for a budget on off style fixture a T5/LED is a decent option for those who prefer a more uniform light coverage with some added shimmer. Something more related to a direct replacement for a MH/T5 fixture with lower heat and electricity requirements. However for a higher end fixture it's not something I would recommend, a mitra looks pretty close to a 250W+T5 combo without any of the drawbacks, IMO it's looks even better.
That said this hobby is, for the most part, expensive and time consuming so do whatever you can justify and keeps you motivated. But for the love of god just do it already
. If you hate LEDs then run Halides, T5s or whatever, don't cry about spending thousands on LEDs because you had to. Electricity isn't that expensive, even with chillers and typically HRV units cost less than $1000 and are easy to install in most applications. LEDs won't always solve your heat, power consumption or humidity problems, usually they just reduce it. Payback periods are long if you can even make it without changing something. So run LEDs if you like them and something else if you don't, justify your decision solely on your personal preference.