There are multiple ways to look at it and it really depends on where you want to go with your career..
1.
www.ecsa.co.za
Converting from a Btech to BSc(hons) eng != BSc(eng). Basically you have to find a conversion course like the one at UCT(2 yr, so Ndip + Conversion = 3+2 yrs) and that can be done from Ndip level provided your results are good. Basically ECSA won't recognise you as a professional engineer without the BSc/BEng. Does this matter? Depends on where you want to go with career.. further up you go the more it will hit you as a limiting factor.
2. MBA programs..
You need to have a degree to complete else have to do a bridge course like MAP/AIM
3. Companies..
If you look at senior positions, you will start noticing that they now require degrees and MBA. What I find is that in CPT, the entry requirements are set high like BSc but here in Jhb they still willing to consider without. How long this will remain is questionable as saturation is occurring due to market being smaller than the peak in 2008 i.e. more grads on offer
For some eng it's still possible to get really great jobs like e.g. sister doing civil eng via a technikon but again.. it does mean later she will have to do a conversion. From what i recall when i was at tech long ago, BTech = BSc but universities are hesitant to let you do MSc(eng) without conversion, in the end I just went to university and finished there.
The tech thing is awesome due to hands on exposure but it is easier to do and companies are under no illusion about this. Personality counts though so if you prepared to put in effort and coast through it i'd suggest going NDip -> conversion BSc as you lose the least time that way(Most engineers take 4.5-5yrs unless they really clever albeit a 4yr program) while getting an excellent bridge between school & varsity, laying the foundation for engineerin and still getting the benefit of BSc with thesis work too.
ECSA kicks in for international jobs and moving abroad with the Washington Accord.. essentially tech qualifications aren;t held in the same rank as degrees so yah it kills an alternative.