Let me take this honour to answer your question. Someone sms me yesterday that there are 123 viewers for your question but none answer, and yet I have a listing for this property that I should give some advice.
Summerdale is an EC and is coming 8 yrs. Currently average psf is in the range $490psf. Your budget of $500psf is very close and should not have a problem getting a unit. Then again is depending on seller if they want to sell at this price. The market is now climbing up and the unit I have, owner is looking at $540psf above. Questions lay with buyer if they don't mind an EC and at this price. Of course it is still affordable at $650K compared with other private condo which is even more expensive for a 3-BRs unit.
For investment, if you can have a 4% rental yield, then I should say is very good. First do your calculation if you are comfortable with first 5% cash and next 15% CPF or cash, assuming you can have 80% loan from bank. Besides, the facing of the unit and other conditions have to be looked at while you are making investment.
Please feel free to write or contact me if you have any further questions regarding real estate. Thank you.