Rownada,

To be fair to either one properties, stay both and make your own judgement, but my experiences with both hotels, I would choose Meridian as benefits outnumber Imperial plus looking where you are from Europe, UK pound for additional RM47 is just ... ;

For Plat member
Meridian; Breakfast buffet in restaurant/lounge, evening lounge (better choices/spacious), Wel Amenity depends in additional to 500pts, Free Internet 2 MB, View (depends on room/suite location) Parliament bldg/city, rate slightly more

Imperial; breakfast and evening lounge only (feel small if crowded/less choices), Wel Amenity in room better in additional to 500pts, free internet 1 MB (slower), view (depends on room/suite location) Twin Tower/KL Tower/city, rate cheaper

Welcome to Malaysia and enjoy your stay ... plus for you to walk from Bangsar to KL Sentral in Malaysian weather if it is hot or rainy, not advisable ... but no one is stopping you for a good healthy exercise ...