PML Cirrus Dart. It is a 38mm minium diameter design with piston ejection. Very easy build, designed for altitude performance. Rouse tech has a 38/240 case that will keep you in mid power with the added benefit of moving up to HP with the same rocket. Also, this rocket can be easily modified with the addition of a 29mm mount for dedicated mid power flying. Solid kit, worth a look.
Just a little bit of advice about the Aspire. Don't glue the thrust ring in because if you do, then you can't fly the G77 and go supersonic. I know that Apogee showed how to modify the Aspire to go supersonic-laminating the fins with paper, using epoxy clay to fillet them and using only three fins. I have also heard that you can buy the parts for three Aspires for the price of one off of the Apogee website.