We use OwnerRez + PriceLabs for a traditional STR we own which I've been very happy with. 

Buy your next deal using a traditional mortgage and your own name.

If those home is paid off and the equity is only needed for a short time, taking out a more traditional HELOC might make more sense.

What factors do you consider when deciding between traditional financing and private money lending for real estate deals? 

As far as loan differences, I'd connect with an investor friendly lender to go over the pros & cons of FHA (3.5%) & Conventional (5%) if you want to go traditional financing route. 

Hard money loans can facilitate faster closing times compared to traditional financing, allowing you to secure and renovate properties quickly.

If your network likes the pure equity play, you should offer that.With the "debt" financing, are you planning on using this as your mortgage, with no "traditional" mortgage ahead of it?  

I'm renting them as non-traditional units (6 of them). 

Usually, this would include something like a holding company ("Hold Co"), typically a traditional LLC, which in turn then owns an investment entity, often a traditional or Series LLC, which will be the entity that owns the assets/property invested into (the "Investment Co").

Yeah you won't get the tax benefits that trickle down to your personal income but that's because in a retirement account there are NO taxes on the gains in a Roth or it's tax deferred in a traditional.