Another 13" vs 15" question with a twist

Hi. I fell in love with my friends' macbook and have decided that I simply must have one. I am torn between two models:

1. MacBook Pro 13 Retina MGX82: i5 2.4, 8Gb ram, 256Gb storage.
2. MacBook Pro 15 Retina MGXA2: i7 2.2, 16Gb ram, 256Gb storage.

The macbook will be used for development. I mostly do C++ right now, but I am looking into android development, so this is probably going to change in a near future. The portability is not very important, but still required, every once in a while I spend some time at my parents' and want to take my development machine there. I also have a 24" monitor which, I image, would come very handy to do serious work.
I was going to buy 15 inch model next week because of the screen size and the additional 8Gb of memory. Unfortunately, I am a little bit late and the prices just skyrocketed by 30% (!) due to ruble devaluation basically over night. But I managed to request a delivery of 13 inch model for the old price (~1400$). It is a very good price, considering the model costs 1900$ in russian mac store since, well, yesterday or so. (Tell me about it, the apple products are extremely costly in Russia)
So, once again, I need to answer the question: is it really worth it to pay more for 15 inch model? One of the local resellers can deliver it for ~2100$. This is really a lot for me and I was on the fence about buying it even when it would have cost me 300$ less.

 

Thanks guys for your answers.

I think I will stick to 13" model for my first mac mostly for the price reason. I just could not justify spending 2100$ on a notebook at the moment.

Yes, this is a great price. Unfortunately, I just missed my window of opportunity.

I almost never play. I use my desktop for programming, watching movies, listing to music and browsing. I could use the 16Gb though as one of opensource projects I contribute to requires a lot of memory to compile.

Yes, that is exactly my reasons why I consider 15". However, the two addtional cores are not that important for me, because the only heavy task I do is compilation. The ssd speed usually has more impact on it than processor power and the flash drives are great no matter what I choose.

What do you mainly use it for?

 

I doubt I can return it. But I used 13" for a little bit and liked it (not so sure how I would feel if I would have to use it every day)