That's your decision, as you need to find a machine that best fits your needs.
My next MBP will be iGPU only. Firstly the Broadwell iGPU is supposed to be much faster then the Iris Pro, which is one of Intel's best iGPU and most of my needs don't require it.
I don't mind iGPU, but the video memory is bullocks. If iGPU can catch up there, i would cry about a dedicated. But sadly at this point in time, theres nothing. As for broadwells increase in gpu performance, thats what they said the 4000 and similarly the 5000 from the 4000, but looks like not much has changed from the ui lag issue of the 13.3". As for the issues for video cards, they have been using nvidia, i know and radeons have issues. I typically avoid and stuff just because they are not aw that good unless its the desktop grade radeons. That red ring of death in the xbox 360 was also due to the same issue.
I am really anal about stutters. I really don't get any with my MBA and i am using it with an external display. 1080p+mba screen is way less than rmbp so thats why i don't have any issues with lag. not even scroll lag on the verge which everybody uses as a benchmark to look for stutters.
I disagree with you that most people don't need one. People who do need one, buy one with dedicated. Especially in the entertainment industry. Musicians, video editors, etc. They don't buy mac pro, they buy 15" dedicated, because they can take their work with them and stuff.
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I would say that you are wrong, but what you write simply just makes no sense. You are just spitting out terminology and have no idea what it means.
Future is in systems where memory is fully shared between the GPU and CPU. The issue is not system memory per se, but the slow speed of the current system memory. Future RAM technology (which is already sampled today) will offer 10x of current DDR3 speeds with a point-to-point connections, making dedicated video RAM completely obsoleted.
Again, complete nonsense. Please inform yourself about the difference between GDDR and DDR etc. before making such nonsensical claims.
Again 10x is overestimated numbers, until they have proven through benchmarks. There is no proof that. Companies over exaggerate these numbers to get people to purchase. Just like broadwells "UP TO" 40% faster gpu. Annand tech proved there wasn't a great deal of difference between the 4000 and the 5000 in gpu speed with the macbook air. average increase was about 15-20%. Whereas intel marketed it "UP TO" 50-60% over ivy bridge.
GDDR and DDR are the same technology, the difference is that GDDR is just dedicated to the graphics card and can't be shared with any other component. On top of that shared system memory has a crap load of latency, compared to dedicated graphics memory. hence the stutters you may get with rMBP igpus.
"GDDR or graphics double data rate memory refers to memory specifically designed for use on graphics cards" straight from wikipedia. look things up before stating that i am misinforming people.
btw GDDR6 is going to start emerging soon while ddr4 is just coming out and will take 2-3 years until all new systems will have them.
Based on what i have seen with apple products, they usually do the "just enough" technique to keep their margins high. the just enough to keep the customer happy. They don't really cater towards power users except for the macbook 15" dedicated and they are still pushing it to the "just enough" standard of theirs.