You mean CMP right?

CMP kits are fine for someone who has a good bit of prior experience putting together ARFs.

If all you need is the C.G. to put together an ARF, then you'll do well.

If you need more guidance, you'll find the manuals lacking.
You'll also find that you should give the CMP planes a good going over to look for any manufacturing mis-steps and potential problems.

An experienced ARF builder will tend to do this anyway and knows what to look for.