M54 vs. M57

[Canadian_E53]

So I'm looking for some opinions, as I'm in a bit of dilemma right now (or a dream). My wifes E53 (m54) is sitting at home in our garage right now with a blown head gasket due to overheating, waiting for me to repair it when I get back home. We live in Canada, where the more common engine in the E53 seems to be an M54.

I'm currently working out of country right now in Latvia until June. There are E53 X5s everywhere, and I mean EVERYWHERE it seems here. The best part...they all seem to be diesel. I however know nothing about these diesels (M57's from my research). Are they good engines compared to the M54? Which one would you rather have?

Part of me really wants to buy an E53 X5 3.0d while I'm here and have it shipped back to Canada.

Convince me not to...or convince me I need to take advantage of my time here and start looking at some X5s.