I have been looking for information on Holborn too. We have decided to use them for the Portugal Golden Visa process.
I can share where we are at so far, and what our experience has been.
First, what we are all calling Holborn is Holborn Assets. Second, when one works with Holborn Assets you are actually working with one of their representatives and their associated team for most all communication and assistance. When considering Holborn consider the representative you are going to be working with as they may not all be as experienced in your area of need or live in a different time zome. In our case my wife just signed us up for an introduction on the Holborn calendar for a virtual video meeting and that turned out the be the person we went with. He doesn’t have a YouTube channel but he is attentive and available when we have reached out. Our representative is located in Cape Town and their team is in Dubai. We are on the West Coast of the USA. At first it seemed like the time difference (9-11 hrs) would be a challenge but in actuality it has worked out pretty well for us. We video conference at the beginning of his work day and the end of our evening.
Here is where we are at so far:
We (Me, wife & Son) are applying by using Holborn’s Navigator Collection product. Were going the 325K route to meet our 500k commitment. Yes, there are better ways to go if you have the dough but we didn’t so this fit our upfront cost needs.
We put forward our 10+K and signed the contract to get things rolling. Yes, if you read the contract you are committed to putting forth this initial sum to pay for the service. As with all legal contracts read it carefully before singing. In my opinion those who complain afterward haven’t a leg to stand on if Holborn is adhering to the contract.
We were connected with a law firm through Holborn but who is contractually separate from Holborn and are our lawyers. They have been helpful answering our legal questions and are available for other legal needs (real estate, etc.).
-We have an individual case manager at Holborn that works with us and she is in contact every few days through the process to help answer questions, and liaise with banks, lawyers, etc.
When we have questions, sometimes the same questions, we set up a video chat with our Holborn investment representative to discuss the political effect on GV or to have the next steps explained to us. Essentially he rattles the trees when things need moving along and he gives us the big picture. We’re pretty satisfied so far.
-We are at the point where we have put forth our 325K, and received the return on investment of 175K up front to add to our Nav. Collection contribution so it meets the 500k PT government minimum. We are currently gathering all our final documents so that when the money is all received we can file our application.
What do we think of Holborn Assets so far? We’re pretty happy. At this point I would recommend them. As a company they have the resources behind our individual representative to aid him with the process. There are contacts, communications, and staff available to us that have made the process pretty smooth. I can get overwhelmed looking at all the requirements and latest news but our people with Holborn have helped me to stay focused on what is important and allowed me to keep my energy where it is needed instead of going down so many possible rabbit holes. 
In the next stage we work more with our lawyers, but Holborn is contracted to aid us through the whole process even through our citizenship applications. I’m sure I will post updates as time goes on. I hope this helps someone else on here.
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