I lucked out with the MP Prime trailer situation. Right after I ordered MP-04, I found someone who was selling the official trailer by itself, so I grabbed that as well simply to have for my MP-01... even though I never transform it to alt mode. But it made life easier so that I didn't have to open the MP-04 set and take the trailer out. I had considered buying the Justitoys version at first, but ultimately decided against it since I think the official trailer really is vastly superior in comparison. And to be honest, I'm one of the few people who actually liked the fact that it didn't come with Roller. I think the addition of it would have been a space waster, and its absence allows for the option of Alternator transport instead... which I like

The MP Megs silencer/stock is a different situation. Even though I'm sure Takara *will* release their own official version later, which I'll still likely buy just to keep MISB as I did with MP-04, I think the Justitoys version will more than suffice for the people who already have MP-05 and I'm sure I'll pick one up as well, especially since I'm already going the extra mile (of geekdom) where MP Megs in concerned. I have a silver plated metal briefcase with dark gray foam molding that I plan to turn into his own MP 'assassin kit' of sorts, so the addition of a stock & silencer is going to make the final package look amazing

I might even take it one step further and get the foam cut specifically for the gun & accessories, hehe.