I think they're supposed to be revving the mbp hardware in a month or two so you might want to wait for that - the newer processors aren't going to be that much faster, but a newer GPU will porbably make a reasonable difference.

Good advice - thanks guys.

I agree with @nomad. It's a sad day for the die hard mac users, when the best Macs today are the 2010 towers with 12 cores built-in, but the power supply is underpowered for today's GPUs and the top end laptop only has a 2GB GPU and costs 2x what a screaming PC laptop does (6 and 8 GB GPUs are available in them!)

The best Mac experience I've had was building a Hackintosh desktop.

The Hackintosh laptops have not yet been able to crack using a discrete GPU, so you're stuck with whatever flavor of on-board intel graphics the core uses (and they usually aren't Adobe approved) in the PC laptops. -I did a lot of research on this for myself about 6 months ago and decided to…. wait (because I can).

The Ultimate MacBook Pro Upgrade For Your 4K Workflow

http://www.4kshooters.net/2016/02/29/the-ultimate-macbook-pro-upgrade-for-your-4k-workflow/

@jleo - the real problem on older MacBook Pro's is the graphics controller. I have a 2012 MBP with a dual-core i7, but Intel 3000 graphics, so it will never play a 4K project in real time. Maxed-out RAM and a SSD won't help with that. Back to the original problem - it would certainly by nicer of Apple to allow RAM and storage upgrades, but it is not that expensive to order the new machine with maxed-out RAM. There is also this:

https://www.bhphotovideo.com/c/product/1239061-REG/owc_other_world_computing_owcssdab2mb05_480gb_aura_internal_ssd.html

@nomad That's interesting. How do you think After Effects would fare on a MBP with 2 GB VRAM?(Are you referring to the dual core, or quad core machines?)

@Vitaliy_Kiselev I have a PC note, but I will be working on some FCPX film projects so need something to handle that software.

I don't know FCPX and do not edit on a Mac but I have not been able to do much with 4K on less the 6GB GPU ram. About the lowest laptop I have seen (unless you are relying extensively on proxies) is this one. https://www.bhphotovideo.com/c/product/1268757-REG/msi_ge62vr_apache_pro_001_15_6_ge62vr_apache_pro.html

I'm not going to try to talk you out of the Mac, but for me the minimum is the HT i7 for 8 cores, with a discrete graphics nvidia chip. Anything less is underpowered. The Sony S15 was one of the few machines I could find with the non-crippled i7 (and you can overclock the graphics chip) but maybe the newer macs offer something just as zippy. The link by @Jspatz has the HT enabled i7 at a good clock speed. I paid $650 for the Sony, used, but the max ram is 12gb so you might want to spend a bit more. As long as it has the cool i7 and graphics card it's all gravy, mac or pc. I purchased for a colleague a high end laptop with super fast chips, tons of memory and a totally knockout 4K display, so there's some amazing tech available.

The top of the line Mac has the i7, but it also has Radeon. Not such a big deal, but it really is better to go with Nvidia. You will have to really do some research to see if the i7 in the Mac laptops are the four core or the eight core, may be the 4 core, cheaper part, (buy cheap, sell big!) or it may be the better part.
I spent about ten minutes trying to find the actual chip name (good luck with that), but on this page it does use the term "hyper-threading"
http://www.apple.com/macbook-pro/features-retina/
Being a cynical type, I would want to make sure what's under the hood despite what the advertising claims-- there is an enormous difference between these two chips. There were some unhappy customers a few years back that got the "four core" chips with hyperthreading, but they were dual core HT so total 4 instead of 8. Ouch. Some of the 2015 desktops had some pretty high end specs, with Octachips, so that might be an option as used they might be good deal and you could upgrade them, possibly.

@matt_gh2 since you are editing on FCPX, it has come to my attention recently that FCPX is outperforming Premiere. Something about how it handles H264, vs. Premiere. As someone still on a Mac and on Premiere, this really surprised me. In the Early versions of FCPX I hated how it was always transcoding in the background and I just wanted to edit natively. Personally, I would investigate this before spending time with FCPX again or investing in a machine for it.

2 videos that demonstrate this edge through Mac's hardware performance. I was surprised myself, with the wimpy GPUs in the machines.

In after effects, I recall the GPU acceleration in CS6 was only used for Ray-Trace rendering. So I don't think the GPU will matter for you, or maybe that's changed in CC?. There are lots of threads on these topics on Creative Cow: https://forums.creativecow.net/finalcutprox