I love the ability to split transactions (it's a "must have" feature for me!) and the ability to separately tag portions of a split transactions is great. But Simplifi would be improved if the split portions of a transaction were treated as separate transactions. Even if they appeared as a single transaction when viewed in Simplifi (as they do now), treating them as separate transactions would solve some of the problems others have identified when exporting transactions. For example, currently, when exported, split portions of a transaction do not display the payee, date, or tags. If they were separate transactions, this information could be displayed for each portion of the split transaction, so that it would not have to be re-entered into the exported file.
Mint has long treated split transactions this way and I see that today Monarch Money added this feature, too. It is more intuitive this way and avoids lots of headaches when dealing with exported files. I hope Simplifi will consider revising how it deals with these split transactions.