You don't need to convince me that you made the right decision
If you need a laptop, then the obvious choice is to buy one. That's the end of that story.
However, from what you describe, you are far from a 'Pro' user. A MBA would almost certainly handle the tasks you do perfectly well. Again, that's not a suggestion that you made the wrong decision - I'm just backing up my point that the 13" is not really ready for 'Pro' users, yet it's marketed under Apple's 'Pro' sub-brand (or whatever you want to call it).
It's all fine you saying "there's no lag", but the majority of, again, 'Pro' users will use the laptop with a large external display. With the known problems with the 13" running its own screen, I can only imagine things get a little choppy when running, for example, another couple of 27" Thunderbolt Displays off it. Problems seem few and far between, however.
Although I agree that benchmarks are largely irrelevant for most, when it comes to a 70% improvement, it's the same percentage difference between a 2009 MacBook Pro, and a 2012 13" retina. That's 3 years of computing advancement...
Benchmark-wise, the 13" rMBP is 3 years behind the 15", and only £190 cheaper. Naturally, this isn't exactly true, since squeezing that much power into a 13" tiny case requires a lot of technological advancement - but it can be used as a guideline to see what you're actually getting with a 13" rMBP.
It's not got the specs for 'Pro' usage in 2013, I would still argue. I'm more than happy for people to point out flaws in my argument, so long as it's not done sarcastically. I'm not a 15" rMBP owner trying to make a point, I'm an owner of a 4-year old MBP who seriously wants the 13" form factor, but with considerably better internals.
While I agree a MacBook Air is a nice machine, the display is nothing compared to a retina display.
I think the retina display sells the rMBP whether 13 or 15in. I have no issue paying more for that.
I kinda have to laugh at the idea of far from a "pro" user. While a quad-core and 16gb ram makes for a nice machine and reasonable desktop replacement, I find it hard to believe even that avg. 15in buyer ever comes close to using the power.
Many 13in rMBP buyers are looking for a solid laptop at lower price point with the best display around. I no longer need a powerhouse machine(I loved building my desktops and watercooling to O/C my windows machines) but never used the power except to game.
No laptop can replace a desktop as a gaming machine(I dont game anymore
)There are no real good windows laptops that compete with the rMBP, 13in or 15in.
The "Pro" is just nomenclature to me, 13in is the entry model to the retina screen and 15in is larger screen and more power thats all.
