Pros & Cons .... hmmmm ?
It really depends on your CURRENT economic situation and the central banks objectives. The noble objective is to have economic stability so business can run as usual.
Using foreign reserves:
The main purpose of foreign reserve is to support own currency. Msia and other emerging countries learnt their lesson during the Asian Eco Crisis. Thus, BNM using it now for that purpose is correct... imo.
As for the other countries.... maybe their foreign reserves are not strong OR there is no perceived bubble in their economy.... I'm just guessing. This deeply depends on their export capability. If your export is good, your foreign currencies holding is more. So weaker currency improves export which translate to improve foreign reserves. BNM may let RM be low for awhile in order to replenish the foreign reserves required to purchase their bonds.
Using Interest Rate:
Increase interest rates helps to bring back hot money into their economy hence raise their currencies. It's like Bank A give 5% in FD while Bank B give 3%.... ppl will deposit their money in Bank A. So in this sense, we are looking at countries. However, this have side effects.
Raising interest rate will also slows down economy. Businesses may hire less or opt for VSS if the financial obligation is too high. Since 2008 subprime crisis, interest rate has become impotent tool to balance the economy. Quantitative Easing (QE) by USA also make it really difficult. Printing money (QE) flood the world with cheap money (low interest rate), inflating bubbles in every sector of investment vehicle. Top 3 economies in the world are doing that .... USA, CHIna & Japan. China is different that they peg Reminbi lower to USD.
Central banks need to play a balance game with a correct interest rate. But with boom and bust in economy, this is getting harder to dampen the swings. However, I believe BNM is prudent. They kept BLR at 6.x% for sometime. However, banks were lending out BLR - 2.x% giving an effective rate of 4.x%. This is due to QE earlier mentioned. Competition with cheap money. BNM is coming out with new framework for housing loans. Base Lending RAte (BLR) means BASE or the lowest rate. Banks broke that rule.....
That's why economist with Austrian and Minsky background cry foul when Fed Reserve (USA) started QE. They expected FED to increase interest rate instead.

Vely well said. Beta than many cut not paste articles provided previously. Bravo boss.