Doesn’t really matter if you do demanding tasks on battery power - your laptop won’t last much in any case. And yes, there will probably be more heat. Nothing your computer can’t deal with. A different question is whether you’ll see any improvements for your tasks with higher-end graphics. I doubt it. But one wouldn’t know without testing...
I don't think it is that common in anything other than that particular model. It may also be a bit more prevalent within the industry, except Windows laptops only last 2 years so you never reach that stage of life.
No immediate disadvantage to having something more powerful, other than it'll be more noticeably less high-end when the next high-end trumps it.
On the other hand for your use it won't make a difference, only your bank account will feel the disadvantage.
I wouldn't call it a "track record" when it's just two GPU families that have had that issue and I'm saying this as someone who's owned two Macbook Pro's, both of them susceptible models that succame to it (and were fixed under extended warranty for it). We're talking about the GTX 8600 in the mid/late 2007 and early 2008 machines and the HD 6000-series in the early/late 2011 machines.
If you don't require external display card just don't get,
The laptop (both PC and MAC) with discrete display card will generated more heat,
more complex and more easy to failure, as discrete card is hungry of power at small room,
which tax the power supply and internal power circuit tired and high temperature.