New roof or not on owner home

[Sam Dal]

guys - this is for my live-in home (not a rental) and I'm trying to evaluate and make a financial calculation if it's worthwhile getting a new roof. It has a slate roof that' s a 100 years old and replacement with shingles will cost 17k and comes with a 10 year warranty. I know shingles roofs often start having issues at the 10-15 year mark. Currently, my slate roof has gone through some repairs and I've spent about 2k in the last 2 years and I think my annual expenses whenever there is a leak will be about $1000 a year. However, this kind of roof has quite a bit of longevity left on it. With a capital expense of 17k, that's opportunity loss of about $1000 a year, What do you think I should do? Also, I've been lucky that the two leaks I've been hit with were relatively slow leaks - do most roof leaks start slow or could be very much the contrary and I may land up being penny wise, pound foolish

If anybody wants to recommend a roofer that'll be cheaper than the quote I've gotten and often works with landlords, I'm all ears - NYC area

Thx