I've ridden lots of different motorcycles over the last 40 years and other than a 1991 Suzuki GSX1100F that really did need to be hooked to battery life-support every minute that I was not riding it, all my BMWs have done very well without tenders at all.
Granted, I live in northern California, 45 or so miles south of San Francisco, and my weather is great for riding 365 days of the year, I've never suffered from any failure to start for as long as I've had my Beemers, which are ridden at least five days a week.
The current bike I ride as a daily commuter, three miles to work and three mile back with the occasional ride to Half Moon Bay to eat lunch, is a 2004 R1150GSA that has a nearly three year-old PC680 Odyssey drycell motorcycle battery that is still going strong, despite the fact that it has never been placed on a charger. Since I read another post tonight concerning a battery tender that wasn't able to properly charge the battery, it got me wondering why would anyone else in similar conditions (especially during the summer) need to worry about charging their batteries if they rode daily and made sure that the bike was charging properly?
I'd appreciate hearing your experiences and opinions!