Experience with Granite Telecommunications as a DIA Provider?

For a new retail site the only provider the landlord will realistically allow us to use is Granite Telecommunications' Granite Grid. I've never heard of them and I'm wondering if anyone has experiences, good or bad, with this provider? We plan to just buy Dedicated Internet Access (DIA) from them, but I'm curious about experiences in general as well since they offer a range of MSP-like services as well.

From what I can tell they are just providing fractional reselling of a larger fiber DIA from the local telco (Verizon) split among tenants. Their sales folks were not at all technically knowledgeable about the product, though I have an engineering call scheduled to try and get more details. It worries me that they are talking about connecting our new-construction detached building with a single Cat6 line into the main mall building and the sales folks thought that was totally normal. The only docs about Granite Grid online look like sales and marketing materials with no technical data and that compare it to DSL and DOCSIS rather than other enterprise or medium business providers of DIA and MPLS. Glassdoor and other employee reviews are pretty mixed, and are mostly for sales positions rather than for network engineers and technical folks.

Typically we use Verizon or Lumos DIA at retail sites, and this feels nothing like buying from them so far.

Thanks!