Has anyone tried out either of the alternative 6 volt batteries that are now available.The first one is a sealed lead acid battery that is 18ah and measures 3.6" x3.3" x6.5" available from battery-web.com for $48.00. The next one I located is an 18ah gel battery available from Great Plains Cycle. The dimensions are very similiar to the the first battery but this one cost $72.00. Neither is a direct replacement, but neither have the dreaded vent line either. If anyone has ever used either of these I would like to hear your opinion.