Estatereal,
1. The seller perception is always with the bigger brand. Remember they only sell every 5 to 8 years. They only remember what is out there. If Coldwell Banker is the biggest then they think it is the best. When you are at the listing table and you work with a reconized brand (Coldwell Banker/Remax/etc), you dont have to sell the company. If you work for your own company or a small franchise you must sell your company. Real estate is hard enough as it is. Currently you have to sell your company, yourself and your marketing plan, unless your dealing with a past client or someone from your sphere.
2. Have I lost some deals because of me moving around? Honestly, probably. Would I ever recommend someone working at as many agencies as I have, no absolutely not. However, I do know how each company works in great detail. I also know the mind set of each agent at these companies and I know their weak points.
Hope that all helps...