BEMONT INVESTMENTS, L.L.C., by and through its TAX MATTERS PARTNER, Plaintiff-Appellee-Cross-Appellant, v. UNITED STATES of America, Defendant-Appellant-Cross-Appellee; BPB Investments, L.C., by and through its Tax Matters Partner, Daniel Beal, BPB Investments, L.L.C. Tax Matters Partner, Plaintiffs-Appellees-Cross-Appellants, v. United States of America, Defendant-Appellant-Cross-Appellee