I don't think that's a concern unless you're growing pretty difficult plants. If you have extremely demanding species, your situation might be different than mine.
I have two 36" 24/7's (purchased at the Co-op) and around 8 Finnex Fugeray's (used units, also from Cory). I also run T12's, T8's, compact fluorescents, custom LED's and cree bulbs from Home Depot.
First impressions: the 24/7 is fun. My interaction with my fish room is schedule based...I leave for work fairly early, and come home relatively late. The majority of my lights are on timers that start around noon, and turn off after I go to sleep. That way the majority of the time I get to spend in my office is also time I see the fish (and feed, change water, etc).
The clear benefit of the 24/7 is the different impressions of what you're lighting at 5:30am, 7:30am...(long pause while I work)...and then get home to put kids to bed (7:30pm glimpse)...9pm (maintenance), and midnight. The shortcoming is that all the time I have every weekday to stare at them...the tanks are barely lit. (If the light is mimicking the light your tank should have at 9pm, it will be relatively dark. Right?)
Before I got the 24/7's I had a few Fugeray strips plugged into non-switched outlets for a little 24/7 light. (I have around 30 tanks in my office, and it's a pain when the whole room clicks from crazy light to pitch black instantly via timer.) The 24/7 strips do a nice job of bridging that gap (there is always some light, and usually, it looks great). However, on their automated schedule, some of the fish I like to see the most are dark when I'm there to see them. To be fair, with two clicks of a remote you can set them back to max to enjoy the color...but that seems counter-intuitive to the purpose of the light.
Plant growth on my 24/7 tanks is good, but I have to assume a comparable light running full power all day (instead of starting low and finishing low) will do more for the plants, especially if you're optimizing with nutrient dosing and running co2.
I like them, and would recommend them. My only complaint is that they run fairly warm. In the future I'll buy at least several more 24/7's. I would have loved to see a few more features, but for their price range, these are some of the nicest I've used.