I think the biggest drawback is the high probability the properties will always be C/D and when it comes time to sell, the buyer pool will be limited to investors at little to negative appreciation. 

@Steve Vaughan - Seller financing is something we've considered, but have a lot to learn in terms of what goes into that and what some of the contingencies and drawbacks are. 

If I do X, then in Y years, Z will occur, and we're 85% sure of that outcome, based on the model"There are definitely times a model has been incorrect (it predicted something, but the real outcome was different)...but, even when a model is wrong, it teaches you something--and with that info, you can make even better models.Another drawback of building the models myself is that it took a lot of time--I probably could have saved time by adapting an existing model...I initially tried to adapt some existing models I found online, but they weren't easily adaptable to my specific circumstances/variables/goals/usage--which is why I ended up building my own models...

My biggest drawback Is money.

Sounds like the only draw back is that they are in only 12 states. 

The drawback I see and I am all for vengeance in certain situations is you are guaranteed never to collect and it leaves their record.  

The main drawback is the monthly fee for the Plus version, which you need for multiple properties. 

The drawback is that it has a lot of fees, so if you can, stick with construction financing.Construction loan interest rates can be fixed or variable, which means they fluctuate based on the index to which the rate is linked.

Lenders will use long term rental contracts to account for income to help you qualify for the next property, so MTR has that drawback.

The main drawback with ARMs is that after those 5-10 years of fixed interest, you are subject to the market rates.