It really depends on your clientele. BC is great for building a business' first website and to incorporate things like email campaigns, in-context site editing, secure zones and eCommerce.
If your client has a very specific eCommerce setup that isn't covered in the BC eCommerce suite then since BC is a proprietary system and you cannot code server-side processes to customize a lot of it, you might need to use another solution for eCommerce.
If I were you I would try to adapt most of your clients to BC since using BC will cut your development and design time over a traditional PHP development setup. But in order to do some advanced things on BC sometimes we need to have a subdomain off the main domain for a client that is a standard PHP setup.
I've been using Heroku's free PHP hosting for some of my client sites for those cases so I'm not paying for it but if it's a highly frequented site you might have to pay Heroku so that your PHP hosting doesn't crash (the free account has limited resources).
You could also do a reseller account too and have a BC account and reseller account but I don't recommend GoDaddy for hosting. Their domain name services are great but I would use a reseller account elsewhere. I used a place called http://railsplayground.net before and I can say they have great support and uptime. For $20 - $25 a month you can have a very substantial reseller setup using the standard CPanel/WHM to manage your account.
If you do plan to use BC for clients you need to be a paid partner. Paid partners get to have a partner portal where they can setup their own billing prices, create new customer sites and rebrand the whole BC solution for their customer's admin areas.
Thank u for taking the time and providing great food for thought. I think
I will give BC a go.