Does the 175 normally come with a cap for the colour cup?
I thought caps were usually reserved for gravity fed brushes.
In any case, I think it's a moot point. I'd definitely keep the 175. I haven't used one, but hear they are a pretty good a/b from others here on the forum.
I have a paasche H which is siphon fed and it doesn't come with or require a cap for the colour cup, so i'm assuming the 175 wouldn't need one either.
If you were using so much paint that there was a risk of it spilling, i think you'd be switching to a jar in any event.
loggerbruce70 is spot on. The a/b will last a lifetime. Spraycans won't. Also, spraycans don't offer much artistic flexibility when it comes to painting. They won't compare to an a/b.
Further, if you've got a great compressor, you're made!
As for maintaining an a/b, there are a heap of articles out and about on how to clean and look after them.
A great starting point for you might be Don Wheeler's website (he's a forum member on here): https://sites.google.com/site/donsairbrushtips/home
Don has a heap of info on that website including a review of the 175 - take the time to read through it all, you'll learn a lot.
Good luck and look forward to seeing some of your builds painted with the a/b.