It's very tough to predict now, and yes, BJ is might be called as MK wannabe due to a number of highrise under construction where MK had established it's name as the best streets of the finest condos available, thanks to Alan Tong's foundation.

But, don't you see the market of MK had been stagnant and I found something missing in the MK ... I think very soon, BJ could overtake MK ... In most of the new home buyers, attract by the name of Mont Kiara and didn't found the catalyst of BJ or any other area, but seems, people already accepting RM 650 psf and above in other certain areas, such as Ara Damansara, Uptown PJ and few more to list on ...

For the KM1 East, it would be very different situation compare to others such as KM1 West, Twin Arkz and Treez in half upper category compare to KR1/ KR2 / Rainz / ZR / Covillea .... where currently, it was the only condo launch with starting price RM 1mil onwards and the smallest unit was 1,873 sf to 2,031 sf ....

If BJ are really explode into the property hot market by 2016 or 2017, I am not surprise if the 1.3mil unit the riches bought now would reach RM 1.6-1.8mil then, hence, I would say, with their holding power, they can even hold at least 2-3 years vacant and throw to the market at RM 1.8-2.0mil ... bcz the competitor within the BJ corridor was only KM1 East itself due to it's tag of min sizing per unit ...

If the RM 1.3mil unit they bought now and reach RM 1.6mil in 2016, I doubt they will sell.

Twin Arkz and The Treez would play a different role in a more Greenery and Eco Friendly lifestyle living ... but some riches I met, and interviewed do not wanted to buy a 2,000 sf + unit within a condo which comprises smaller sizes, i.e 720 sf unit or 1,300 sf unit but they wanted something all big units only condo for exclusive and privacy profile for each other ...

seems that the rate of appreciation of certain props in BJ pretty good close to DPC.. 
I only can remember Savanna from 200k+ to 600k+ in just 5 or 6 years..