It really could go either way - and it depends on the neighborhood you're in and if your pencil on the property requires immediate rent increases.

I feel confident that this property would require 20-30k in rehab costs, but is would increase the ARV to around 120k or more.

New layouts, moving walls or god forbid an addition...you’ll tear your hair out with SF’s nutty city approvals, and your neighbors will be all in your business if you’re increasing the size of the home. 

But others won't be able to afford the rent increase and will either have to find a cheaper and lower quality place, or stay and fall behind and have to be evicted; others will,leave because they are angered. 

I always try to pay for what’s in front of me and try to not speculate on rent increase etc. if I do manage to increase rents or pass expenses off to the tenants than that extra money is gravy. 

Your CPA might be confusing Bonus depreciation with 179 expense deduction. 179 deduction which was also increased to 100% with the tax reform can only be applied to non-residential property.To clarify, the 100% bonus depreciation applies to property that has a useful life of under 20 years.

Has your business substantially increased or changed due to having it? 

On paper, he would be able to make $50,000-$100,000 annually on increase in value of the property he had debt on. in that timeframe, the amount he was making on paper was significantly higher than what people were making on annual salary.With that thought in mind, I would lean towards the content of leverage is King.

I really thought I would be asked to increase my offer if their were other offers.

I wouldn't trade my life for a corporate job even with a 30% pay increase.