Are you going lowtech and lowlight? If so there is no need for a T5s. Usually the tank will then require much more care and maintenance. You need so much more items as well. I have Seachems Nitrogen, Potassium, Phosphorus, Trace, Flourish, and I plan on getting Iron just to keep all the nutrients in balance. My tank is "hightech" so yeah. I would recommend T8s more for a low to medium light.
You can buy shop lights and suspend them over the tank and have two bulbs just not as much light. The estimate for T5s compared to T8s is 1 T5 =1.5 T8 bulbs. Of course it depends on reflectors and bulbs as well.
I do agree that canisters are better for a planted tank as you can control the surface agitation. I would use a zoomed canister filter.