Re: Get a new Mac now or wait?
Taking your points in isolation...
Flash storage on my rMBP does really make a difference, fast boot, loading of apps, accessing and writing video/images to and from storage - as you would expect. For me, I am surprised at home much I like the fast wake and boot. Like an iPad, almost instant waking and super fast app loading.
Storage - Flash is expensive, so if you need a lot of on board storage, then the rMBP is an expensive and limiting option that will impact as a factor that you need to decide upon in terms of compromise. Alternatives might be Thunderbolt or USB 3.0 external HDD storage. Really cheap option and still super fast read/write access speeds.
Retina Display - it is awesome and I find it a really jarring experience going to any other non-retina display (except the iPad Mini which I forgive because its just a great form factor and still totally iPad). Again, you have to decide on the balance between want versus need. The Retina display is amazing.
Windows 8 on your Mac - my first question would again be to ask whether you need it or just want it. From people that I have spoken to and seen commenting online, most Win 8 users want to drop back to Win 7. Lots of commentators mention that Win OS often are only good every other OS. Vista was awful, I found WIn 7 to be quite nice (for Win OS) - that leaves Win 8... your call - need or want?
If you use Bootcamp for Win 8 - you may need to consider the impact on your available storage as you are likely to have a pretty big partition to hold the Win OS and then some space for the inevitable and frequent updates. I say this as someone that had a problem on my old MacBook. The effect of this would be significant if you go down the route of the rMBP with SSD. It might be worth looking at your use case and consider if using a Virtual Machine solution booted from a USB 3.0 drive would be a viable solution. I used to do this with a memory stick each for XP, Win 7 and Linux.
My final bit of advice would be to say that you are never going to have a computer (particularly in the case of Apple) that is the latest and greatest for long. (My rMBP has already been updated since I bought it in Dec). You will often hear about minor upgrades (such as the recent rMBP) but the only thing to check if there are any logical / typical major changes coming in line with Apple's release schedule. Be careful of the desire to have the very latest and greatest - if a new one comes out, it is unlikely to really adversely affect your productivity and / or enjoyment. There is a risk that prices and specs might change but you simply can't let that affect you too much.
Just my twopeneth, hope it helps.