Years ago, on the Palm and later Treo, I used SplashID, but ultimately switched to eWallet. I preferred the interface of eWallet, especially on the desktop-- and most importantly, the sync just worked, without hassle, each and every time. When SplashID showed up in the App Store, I first ran to grab the desktop from their site. 15 minutes later, I returned to the app store, but purchased eWallet instead. I have since received an email from Ilium, directing me to a page at their site to grab the desktop (free to prior users). It's version 6, but the next 6.x version will be the one with iphone-friendly goodness. The current version is enough to bring in all my stuff now, so I'll be ready when the iphone sync appears. Looks like they're adding some sort of wizard to preclude problems for those who've not used ewallet before, and it should be ready within a month or so. I've learned thru the years that I can trust Ilium, so I'm confident it will be worth the wait.
Meanwhile, I no longer have to be concerned with a syncing notes app, as I just use eWallet's "Note" card. This is the one app that doesn't crash, so I'm a happy camper.
Suggestion: if you've not yet made up your mind, grab the trial version of each one's desktop app. That's where you'll be spending most of your time initially, inserting what you have scattered around now. Check out the import feature for each, which may save you some keystrokes. My hunch is that your desktop experience will dictate your iphone app choice between these two. Go with what works *for YOU*.