Amtech is a slightly clunky design tool for those designing to the requirements of BS 7671, and makes a fair effort at producing the document package typically required by an installation team. It generally produces acceptable, if sometimes conservative, solutions although its libraries are limited and it imposes certain limitations on what it is prepared to calculate which can be frustrating. Amtech as a company has some of the most persistent salespeople I've ever encountered - at my last employer one of my colleagues told them I was DEAD before they finally gave up on the endless phonecalls offering deals, upgrades, support packages, etc. Give them your phone number at your peril!
Etap is a very different piece of software for network modelling, load flow and fault calculation and so on. As a design tool it is considerably more capable than Amtech in many ways, and correspondingly more complex to learn, but it's not a BS 7671-specific tool for producing cable schedules, test sheets and so on.
