Pro version is paid by state I believe and has extra owner info (ph numbers etc) and custom CMA tools so you can generate an autoval for a client with your own logo.
Owner data is highly useful for developers looking to buy off market sites.
CMA might is good for agents who want to build their brand(selling agents use it for the pre marketing appraisals to vendors - they have their logo all over their reports they seem obsessed with that sort of thing). Same data in the cheaper version CMA afaik so no need for this really if you are an investor.
If you just want to analyse feasibility of a couple of purchase properties the cheap group is fine it gives you the sales history and local comparables, plus a basic mapping tool. Nearmap is better for that but it needs a separate subscription.