I've been running a small software/web development company for more than 10 years now and I run into this issue quite frequently. Not as often as I used to, but still more than I'd like to. I found some years ago that it is important to follow the 80/20 rule. That is, 80% of your income comes from 20% of your clientele. Your clients aren't afraid to fire you, so don't be afraid to fire them. If they want to demand 100% of your time, then they aren't worth your time. That being said, generally each client regardless of their budget thinks that their project is the most important.
Your job as the leader of a small tech company is to be apprised to what your people are doing. In most cases you don't have to tell them who is working on the project. But you need to have a proper project management system in place so that when a client calls, you can also figure out what is going on. Also, if you don't have an architect working at your company, then you are the architect. :) You should most definitely define the architecture for your developers, throw that in your project management system, make your devs give detailed updates in the PMS, and consider daily SCRUMS, so when a client calls you don't sound like you don't have a clue what's going on & send him over to one of your devs. Generally speaking, devs aren't the best people to put in front of your client. Remember before you started your business and your were just a normal programmer without a business. When you went to a client... didn't a "handler" always go with you (project manager or some other sort of manager)? When devs that aren't accustomed to dealing with customers start talking tech, the customer's eyes glaze over & they usually get annoyed. So, you really have to be the point man.