Conventional is better as Memory Blocks are VERY Slow Commands in AGK...
This is especially true in regards to Creation and Destruction scaling somewhat exponentially with size.
Try timing loading 1920x1080 Images as Images., then as Memblock Images; you'll see what I mean.
In Dark BASIC Professional they're fast enough to really be an excellent and powerful too... functionally in AppGameKit they're just as versatile, but performance wise; it's so bad that you'll want to avoid using them as much as possible.