I do save up most of the stipends from my alt accounts.
In truth, I think very few of us actually do that - at least not on our main accounts. The part about only costing $1 US per year only applies if you save all of the L$300 stipend paid to you throughout the year and cash it out to pay towards your yearly Premium renewal fee. Additionally, I have numerous alt accounts that are also Premium. Yes, I am a premium member and have been for almost my entire time in SL. However, only you can determine if it is worth it or not. perks (priority entering events) I'd definitely say that the benefits got better over the last year. Since LL increased the tier allowance from 512 sqm to 1024 sqm, and added a few other misc.