I got the CopterX 250 because the HK-250 IS NEVER in stock.
CopterX 250 = $55 SHIPPED!
I did get lucky and got a HK-250 when they were in stock (2 hours and were sold out) $30 shipped.
I have been buying the EXI parts for repairs
To me CopterX is a better kit and worth the exstra cash because it has better quality Over the HK-250. My HK-250 had a weak belt lasted one hover, blades broke off at edge of grips when I was tracking them, and no my head speed was not to high the CopterX and EXI plastics are not as weak.
I don’t have the EXI kit but parts seem to be as good as the CopterX in my opinion. All 3 kits so far have been compatible with each other.
This size helicopter is a challenge to build; it is NOT a beginner helicopter I have been flying and building the 450s for years and the 250 has really humbled me. You will either become a better builder and flyer or you will give up on this size. I love this size for the small back yard Batteries are cheap and they do not take as long to charge so I find myself flying more, but also crashing and rebuilding more. Most buy one of these clones blame the kit, give up on it get a Align 250 forgetting that they just learned new building skills. Some stick with the Align kit some will sell that off.
My 450s collects dust but my 250s I #&@$* at a lot more. YOU WILL LEARN TO USE LOC TIGHT AND LET IT DRY!