I'm going to pick up a POD in order to review the compressor modeling in it. So which one should I get? That's really a few questions rolled into one: First, which one has "the most" or "the best" compressor models? Second, which one is most easily upgradeable (by downloads or whatever other method)? Third, which one is most commonly used these days, is it the XT or the XT Live or the Bass XT (or what) that most people are buying? And lastly, if I buy the "most common" one will I be missing out on any must-try comp models, or will I be missing out on upgradeability? Let me know if I need to make any of that easier to understand. Thanks!