I've been using Metastock for 14 years. It still has the most beautiful charts, and also has a very useful explorer that I frequently use to find targets. I do not use the backtester as I am purely a discretionary trader. If I think of a strategy I can quickly code the signal and drop it onto a few charts to see if it's any good. Whilst its language is not as powerful as Amibroker, Tradestation, etc, it's easy to understand and work with.
What Reuters needs to do with MS is to shift its focus from adding more systems and indicators to adding features and improving the product's flexibility. I have little use for their systems and do not need any more indicators, so the only reason I have to update MS is if my operating system does not support it.
As for Reuters data there is no need to use it if you stay away from their QuoteCenter version. Use the EOD or esignal version instead.
In short, if you are a discretionary trader MS is a very useful tool that can make you money, but if you are into systems you'd best look elsewhere.