I like the 1.5g carts, they work well with my big battery, a yocan uni s. They may be a bit much for smaller batteries or the old ones you screw the cart on the end of.
As for the HHC...
I'm about half way through my first cart(about 2 weeks in) so anything else should be out of my system by now.
For me it has a very sativa like effect at low doses and decent body buzz in higher amounts.
In all, I'm very satisfied and will be adding HHC products to my inventory.
I have a feeling this stuff will be very popular ;)