I would only switch out to another brand if it could put out the same cranking amps as the harley battery.. When I first put in my 124" motor they tried to sell me a new battery and high torque starter. As it turned out, S&S was on site and told the shop owner that this combo wouldn't turn my stock motor over fast enough to make the bike start. S&S finally told me to go to Daytona Harley and buy a new starter and buy a new Harley Battery as the cranking amps were the highest and that the Harley Starter was far superior for bikes due to the speed at which it turned the bikes over. I brought back the Harley Battery and they put in the Harley starter and it cranked over with but wouldnt start with the other battery and the harley battery so then they put in the battery as the shop was trying to show them it wasnt needed to buy the battery. They Put the HD Battery in and first shot it started.
Not sure the story helps here, but without both of them in the bike together the motor wouldnt turn over fast enough to start it. I wouldn't say that other combo's wouldnt work out there, but this was something I saw first hand and has always worked well for me since that lesson.