Found myself seriously considering buying ER Arcee just to apply that kit, but then went hunting for a comparison of ER and Legends, which I don't think I'd done before. I think I'll stick with the Legends one. That at least turns into a car and doesn't look too bad.
Grimlock set is better. I got the orange sword and lightly tinted chest.
Confession: I hate the "dinobots get orange and black swords" trend started by the FoC game (who's terrible designs I also hate in general). But I feared that without pictures, the red sword option would be solid red, which I felt would look terrible. At this premium scale, the hilt would need to be a different color to not look cheap. I was right.
The lightly tinted chestplate is easy to install and looks tons better than the nearly opaque original. It also looks better than the clear alternative, imo. The crown was superfluous to me, and I didn't particularly care for it's inclusion. Grimlock getting a crown at this point is like Starscream's Coronation gear- it's become so common that it's lost it's novelty factor. But having it, this one is well done. Don't actually mind it.
Now for the rest: He didn't match grimlock's plastic well at all. The grey pieces for the teeth, screw fillers, and arm covers are significantly darker. And the gold stands out, as well. Not so much for the crown, but the neck screw filler it does. I ended up not using the screw fillers, because I think they would stand out worse than the holes do.
All in all, I don't think it's worth the full price. I'd personally have been happier with the sword and chest cover, at a bit lower price. I like what I got though. Your milage may vary.
Ariel Lemon's models are normally fairly detailed by the time he makes them available, and are generally really good. I got one of his conversion kits from Shapeways, and the Conjunx has a few of his kits.
The mad thing is that because it's scaled to TR Blaster, it's way too big for all the other figures in the proportion it appeared in the film. It's a massive accessory useful for only TR Blaster and Soundwave.