Ok, what is the difference between IMBC and SMBC ? Which one do you think is better? Is one easier to make and is easier to work with? Thanks!

There are quite a few different recipes for both, so i can only comment on the two that I use. My IMBC and SMBC recipes are nearly identical. Once finished they taste and handle exactly the same. The only difference being, obviously, being the technique through which they are prepared. Swiss, I feel, is easier to prepare (at least for those not comfortable/familiar with cooking sugar to various stages). Also, an Italian meringue is more stable than a swiss, therefore IMBC is a slightly more stable product.

Everything you ever wanted to know about meringue buttercreams:
(Includes definitions, recipes, and so much more.)

http://forum.cakecentral.com/cake-decorating-ftopicp-6011626-.html

HTH