It's a bit of a catch 22. You won't know what's under there until you take it down, but once it's down - it's down.
Is there a smaller section you could start on? I took down the trim from my front door overhang first. I chose that area because I couldn't imagine anything could look worse than the aluminum. Lol...I was wrong as it was pretty rotted out. But, it was pretty easy to fix....took a lot of time, but not much knowledge.
Then I took down the trim from a bump out section. The wood underneath there was in great condition. It just needs paint.
That got my confidence up and the rest of it came down this summer. I definitely understand the "what if I'm getting myself into something too big" feeling. I'm doing my restoration by myself. But, I decided that the worst thing that could happen was that I'd take down the aluminum and there would be a bunch of rot.....but I decided at least then I would know what I was facing.
My house is less than beautiful right now. All of the wood needs to be stripped & repainted. Some needs repair. I've spent weeks caulking the gaps & reattaching trim. But it hasn't been expensive. And while it's really slow going, I think I'll be able to do it all pretty easily. I'm aiming to finish painting the front before winter. Then next summer will continue on with one of the sides, etc.
My neighbors watched this all pretty closely. I let them know what I was doing at our block party. By then I had painted my storm door with a bunch of paint samples, so I asked for everyone's feedback. I'm sure a bunch of them think I'm nuts, but a lot of them "get" what it is I'm working towards. The other day, and older man out walking his dog stopped me to tell me he had been following my progress....and then let me know he did the same thing about 10 yrs ago.....and that it was worth all the work and his new paint job was still going strong. So, don't underestimate the friends & family coming around.....
I also planted a whole bunch of flowers this year, to balance out the paint ugliness
Whatever you decide, good luck!