I think the experiences with consultants vary quite a bit - even the same ones. I have seen people clash or click and it really depends. I would say the biggest cause of friction is expectations and it would be great to set them straight - e.g. how fast do you get the edits back, who drives and reminds who? I have had people who had to remind and bug and manage their consultants like a PM and they did not think it was worth the money because that's the last thing they expect to do while paying $5K. However, the project managing is often falling on the applicant which is pretty crazy but it is esp often during the busy days right before the deadlines.
I am sharing just generic experience that I have seen over the years, not familiar with this consultant per se.
I would also say that it is always an advantage to work with someone who is the owner or the manager of the brand. They care to make sure their clients get the best experience (this may not mean you get the best product but you enjoy the process more and they keep you happier) because they care about the brand. An average consultant in a large firm may not care as much as this is their second job, and they have contracted for 20 hours and that's it but that's an over-generalization - there are different people in both types of firms and consultants and there are advantages to be with a large firm, esp during the busy days before the deadlines when the consultants are being torn apart by applicants.
Whoever you choose, they won't be perfect. You will have to project manage them (at least a little), set the expectations for your worth straight from the get go and raise the alarm early. do not wait for the pressure to grow so much or pretend that things are normal on a call (that's the easy thing to do but if you are paying a lot of $$$ you want to make sure to voice suggestions for improvement and stand your ground. You want to be nice and professional but firm - they will know they can't get away with crap.