I disagree there is a lot of benefits to acquiring a Mtech , or any Masters degree for that matter. I am busy doing my Mtech part time, I am handing in about 2 months time. The benefits for me I can say they are the following
Improved writing skills
Critical thinking
Asking the right questions
Respect for other disciplines
Technical skills
Project Management
To discuss the benefits further. It goes without saying your writing skills will improve, writing a 80 page plus document is guaranteed to improve your current level of writing by some margin. Well you may wonder if writing has some importance, well it does if you have seen the level of ambiguity that is present in some people's work it's a bit disappointing at times when you have to go back to the person and ask them to give more information, if more people in this country had a postgraduate degree, I think there can be generally better clarity in written communication as the degree will instil some level of discipline in how you write, you will consider minimizing the pain of the reader.
Whatever your ability was to think critically it will be improved, I can speak for myself in that these days I am very critical of a lot of things, I am less accepting of ideas verbatim. Thirdly you learn to ask the right questions, those questions that tear ideas apart

. Fourthly you will learn to respect other disciplines, especially when your topic takes you on journey where you read articles from Law, Economics, Computer Science, Information Systems, Philosophy, Business. You realise the importance of other disciplines( I used to look down on any other discipline that was not in the computing sphere) and the value they add to the body of knowledge, and how someone from a different field can stimulate your mind so much that it borders on 'erotica'
The other thing it helps develop, if you are producing some kind of artefact as part of your thesis, is that it will upgrade your technical skills, as you are likely to work with technologies you would unlikely use in the workplace, even more unlikely in South Africa. Which I think helps you grow as an individual, and forces you to perceive the programming world differently. Finally you will become a better project manager, as to graduate you have to manage the thesis, and it's no small feet especially if you are doing it part time
Regardless of the feasibility of each (the MTech being the natural progression from the BTech of course), it all depends on what you want to achieve.
Personally I don't see the use of an MTech. If you are going to study more than 4 years the BSc Hons is probably worth more the effort.
For a career, unless you want to go hardcore and do complex mathematical and statistical stuff, a BTech is more than sufficient.
...but again, if you have the means to study, do it. Just don't over qualify yourself or expect a senior position/salary straight out of uni.