my experience is that as a buyer I have not received responses on properties for sale except at one time when a wholesaler was selling a property outside of Abilene Tx in a very small town. 

My question is whether or not I should consider this option to help speed up the sale.

If its the sales side, get your license.

Buy with equity and cashflow, improve units at vacancy, increase cashflow and then pull money out and go do it again.To Your Success!

Also, where is a good place to look for agents that have experience looking for self storage properties for sale. 

You may increase your knowledge of various techniques, markets, funding choices, and best practices by using resources like as books, podcasts, online forums, and instructional platforms.

I've used them for cash sales in less than 14 days, they get it done cleanly.  

As long as you can take title to it within 180 days from when you close the sale of your old property.Or you could do a Reverse Construction exchange where the QI takes title to the lot (before you do) and then the builder builds on it. 

We purchased it below market value and increased the rents from $1000-1200 up to $1400-1500 What was the outcome?

They practice general real-estate law, and do sales transactions for condominium.