Quoted:
I have a factory RRA 9mm carbine that runs like a top and is a joy to shoot. The only thing I can say bad about it is that I had to wait for a long time after I ordered it. I have a 9mm SBR that has many Spikes' parts, particularly the barrel. Very nice as well.
My SBR'd 9 also has a lot of Spike's parts. I went with the Lothar Walther 5" 3 lug and love it. It is a stupidly accurate barrel. Which barrel did you go with?
OP, Spike's sells their complete 9mm for $1125. You might want to see what it would cost for a local FFL to do a transfer for you. You definitely will like shooting the 9mm, it's a blast.