Offroad-Express

With vehicle mounted UHF sets which aerial is better

long ones ??

http://www.dse.co.nz/cgi-bin/dse.storefront/46dbe08900977a0c2740c0a87f330706/Product/View/D4007

or short ones ??

http://www.dse.co.nz/cgi-bin/dse.storefront/46dbe08900977a0c2740c0a87f330706/Product/View/D4013


or one like this ??
http://www.dse.co.nz/cgi-bin/dse.storefront/46dbe08900977a0c2740c0a87f330706/Product/View/D4000

Also ...
How do the spring mounts affect the performance and do they actually help prevent broken aerials

I would just use either that you are happy with, have been with peops who have a selection of aerials and all worked the same.
Do get a spring base as it will give added protection to the aerial when branches get in the way.

My aerial is a fiberglass one about 1M long.