Change y to i ... or change i to y?

Sometimes I find it's useful to turn things upside down. Looking at something in this different way prevents me from just accepting it the way I've always looked at it and makes me consider it more carefully, perhaps noticing things I hadn't seen before.

I like doing this with language 'rules' too. I want to check out for myself whether they are really reliable enough to be useful. I've certainly found some that weren't.

y to i
In English spelling, we often hear, "If a word ends with y, change it to i before adding a suffix". This is generally true but there are, of course, exceptions. If there is a vowel before the y, it doesn't usually change. And there are irregular instances such as say and said.

One of my posts was about letters not found at the end of native English words. It contained a PowerPoint presentation in it called Never-Ending Letters in which I identified i as one of those letters (except of course for the pronoun I). While I was writing it I noticed that it might be a good idea to turn this so-called 'rule' about y changing to i on its head - turn it upside down in other words.

i to y?
What if we said: "Don't write i at the end of a word - change it to y? In other words we're changing i to y (at the end of a word) instead of changing y to i (in the middle of a word). In a compound word we also keep the 'rule' about no i at the end of each part. As well as this, we need to change i to y before a suffix beginning with i, to avoid a double i like we get in the (non-native) word skiing.

So we write tries, tried and trial, but we can't write tri for the first form of the verb (because native English words don't end in i) so we spell it try. And we can't write triing, because we don't have double i, so trying.

Let's look at more examples, to test it out:
We write babies, but baby (end of word), babysit (compound word) and babyish (avoiding double i).
We write happier, happiest, happiness and happily, but happy (end of word), and happyish (avoiding double i).
We write reliable, reliance, and relied, but rely (end of word) and relying (avoiding double i).
We write beautiful, beautify and beautician, but beauty (end of word).
We write said, but say (end of word) and saying (avoiding double i).

OK, it works ... but I'm trying to decide if this is a better way to look at it or not. There are pros and cons.

There are fewer (if any) exceptions. As long as we are talking about native English words, they don't finish in i (except the pronoun I).
The fact that a vowel before a y stops it changing to i becomes irrelevant. If there's already a y, we don't need to change anything.

The base forms that end with y aren't usually the problem when it comes to spelling. It's the longer forms that are usually more tricky. These usually contain i.
When we teach, we usually start with base forms and later deal with inflections and suffixes.

My conclusion
Turning this rule on its head is probably more accurate and easier to understand but would involve teaching words in an unnatural order. So I probably wouldn't use it with low level students, but at a higher level, if students were having difficulty, I might well point it out.

So has this little experiment been a waste of time? No, I don't think so, because it's always useful to question what's generally accepted as true. Another perspective is always useful.

What do you think?
I would love to hear your comments on this.