Or would you use these properties as vacation homes occasionally? 

Mostly because the net income by then will be around $500 or $600 per month per house which is more than enough to handle the occasional big ticket repair.The one thing I will say I understand is that I wouldn't want to have to count on my real estate income to replace my job income at a 1 to 1 basis.

Occasionally, they don't even have it then!

Occasionally you will run across a listing that lists actual numbers.

I agree with Anson that a multi-unit would be great, and occasionally I see one that works for an owner occupier, but you could probably do just as well with a couple condos.  

If you're starting out and need a lower price point to get into a property, if you're not interested in maintaining mechanical or roofs, if you want managed costs (HOA's) versus the occasional big ticket cost (hot water heater fails), they can be a great option.  

I'm wrestling with the same decision myself, on a smaller scale (could sell for $170k or rent for $1200) Similar overall numbers, and by my rough estmate (rent X.7 to pay a manager and expenses including occasional vacancy) minus MTI, it'll have mild negative cashflow, offset by loan paydown.

My wife and I are very excited about this opportunity and we have decided that we want to focus on 2-4 unit multi-family investments with the occasional SFH for buy and hold purposes.

Sure I have strong opinions, and occasionally I am forcefully and publicly WRONG.

For me, the benefits that make it worth it are...1) Credibility with sellers, buyers etc.2) MLS access3) The option to list the occasional property if I want and earn extra cash through a comission4) Not having to rely on a realtor for  realtor related tasks like gaining access to properties for sale.