Playing around does not qualify you to answer the poor mans question. That is just plain uninformed advice and does all a disservice!
I had a late 2013 base 13" rMBP i5/8/256 for over a year. I run Parallels Windows 8.1 Photoshop CS6 (heavy graphics and marketing work) plus a memory hog work program and Chrome (I am trying to switch to Safari but it sucks, period. I got a Early 2015 13" i7/16/512 and it has been a fast improvement. I can chew through anything. plus I get at least two more hours of battery per day.
If you need the horsepower and headroom and make a living off your computer the upgrade is worth it. I will say the small form factor of the new 12" rMB has me drunk with desire and I may sell my new 13" beast, keep the 1.3/256 12" and get a 5K desktop for my heavy listing. Crazy you say? Well with even Delta now shrinking seat space a trip back from Vegas yesterday had me working on my 13" with the lid closed at about 45 degrees. That sealed it me thinks!