This paper focuses on the live migration of virtual machines (VMs) across semi-heterogeneous processors (SH), which share the same ISA but expose different features. Processor incompatibilities in such settings can block or break migrations, limiting resource utilization and operational flexibility. We provide the first detailed study of live migration feasibility across SH processors, yielding several findings valuable to cloud tenants, operators and hypervisor vendors. Building on these insights, we present MigCheck, a simulation tool that predicts the feasibility and outcome of VM migrations across SH processors without requiring costly real migrations. We demonstrate its accuracy and effectiveness through multiple use cases, including machine addition/removal, hypervisor updates, and VM platform adjustments.