I think this is a good deal...if financed correctly

[Ryan Sanders]

A duplex in my area is listed for 197,000. The following information is provided: "This duplex has been totally renovated inside and outside! The kitchens have new cabinets, new counter tops, and new appliances. The bathrooms have new tubs, new vanities, new toilets, and new mirrors. All carpeting and linoleum floors are new. Fresh paint everywhere inside. All the lighting and faucets and outlets are new. More importantly, all the electrical wiring and plumbing and heating is all brand new! Outside has new windows, new doors, and new stucco. Even the sidewalk is new. This place wont need to be updated for decades. All work was done with permits and by licensed contractors. Each unit has laundry hookups for full-size washers & dryers. Plenty of parking."

More info:

Unit 1 rent: $810

Unit 2 rent: $800

Each unit is a 2 bed/1 bath. Last year's taxes were $408.

My biggest concern is that I will not estimate my expenses correctly. I made assumptions that could be completely wrong but here they are:

Property Taxes: $450

Insurance (annual): $500

Property Mgmt: 10% rent

maint. and repairs (annual): $1200

Advertising: covered by property manager

Utilities: covered by tenants

Vacancy rate: 10%

Do these assumptions look sound? If so, and I can find 4(ish)% financing with no money down (i have some creative ideas), then i would have in the neighborhood of $180/month cash flow. Cap rate comes out at 6.72%. Cash ROI: 56.17%. Total ROI 297.22% (only high because no down). GRM: 10.40 (don't really know what a good number here would be). DSCR: 1.20 (also don't know what a good number is here).

I would love any and all feedback on this property and I would also love if anyone is willing to give a bit more info on GRM and DSCR, what they really mean, and what good numbers in those area mean and how important they are on a deal.

Thanks!