The other thing is that these are single pane windows we're talking about. Yeah, the storm windows can add a little extra insulation but they're still going to be a total heat sink, and who likes using storm windows? You can't get a breeze so you have to remove them and replace them every change of season? Don't even get me started on those incredibly frustrating aluminum screen/storm window combos.
No, the discussion is about insulated glass units. Storm windows add nothing in the way of insulation, they do however work to increase the over all performance of the opening to being comparable to an insulated glass unit. No idea why they would be a heat sink? Or what you are trying to say there? When added to older double hung windows, modern, pre-finished triple track storms have none of the negative issues you refer to, and are economical to buy, and install. They make the actual, period correct, original windows in a home last a lot longer, with a lot less maintenance, and dramatically improved energy efficiency.
True, the OP is referring to a double pane window. I should have addressed your statement in particular, as that's what I was thinking of.
I maintain that old windows (and new ones too, to a lesser extent) are a total heat sink if you've ever looked at a house in the winter with a thermal camera.
I won't argue that aluminum track storm windows can offer acceptable performance, but I will say this - they don't do any favors for the period correct, original windows from the exterior. They're ugly and don't match the era. The simple wood storm windows aren't too bad on the eyes, but again those need to be replaced with their screen counterparts every spring if you want a breeze (and then every winter if you want the performance). But even in the winter it's good to open your windows for a bit to allow some fresh air in, so you can't do that with the wood storm windows.
So what do I recommend? A triple prong approach -
For areas where exterior appearance IS important, and you DO regularly use the window:
A very high quality wood window like Marvin that will match your historic home.
For areas where exterior appearance IS important, and you DON'T regularly use the window:
Keep original window and build/use a wood storm window.
For areas where exterior appearance is NOT important, and you DO regularly use the window:
And of course you'll have to use your best judgment when it comes to windows that are close to each other that meet different criteria - you probably want some semblance of uniformity with your windows.
If it's a really high end home, maybe just go Marvin all over.
Hope this is helpful, it's pretty helpful for me to think through all these things as I prepare to action my windows.