Staircase-replace or repair?

You might get more responses from people who've done it on Brownstoner.com

One issue to consider is whether you want perfection in the final product (completely even treads, zero creaks, perfect right angles, etc) and are okay with losing the detail (IMO, no replacement staircase generally comes close to the beauty of the original). You won't get perfection if you're repairing, but you get to keep a little piece of the original.

Before thinking about prices, I would like to ask what your intention is to replace it is. Is not safe?? Is ugly?? Is the repair needed to extensive??
When performing a gut renovation leaving original elements might help in preserving the character of the construction this is true, but if it doesn't really have an architectonic value it might look older when comparing it to all the new work It also might represent a hazard if the condition is not good enough and maybe to fix it can be more expensive than replacing.. In this last cases is typically to regret not having make the right decision when you could. I suggest you ask yourself the question why you would leave it or why you wouldn't.
Then you can make the right decision and find a contractor or company that can replace or fix it for the price you are willing to spend.

In most townhouses I've seen in the flesh or in pictures, where the staircase has been replaced, the replacement has been less impressive than the original. Even in gut-gut-gut renos, where the overarching theme is more modern than Victorian, leaving the original staircase is NOT discordant. I wouldn't say this for all architectural elements.

I suggest you google images of renovated townhouses in NYC, focusing on the staircase.

What's discordant is a preachy peach of a guy tweeting a pic of his erect penis to a college chick in Texas, than claiming Chinese psycho terrorist did it.

Can someonE tweet me a pic of the naked staircase.