Did you look at the docs.marketo.com under Field Management? Did you search for similar threads?
Generally a Type mismatch is a bad thing and will break or corrupt the data somewhere.
Ideally you create a NEW field, push values over, and then deprecate or remove the old field. Lots of tips here on how to create new SFDC fields and get them into Marketo properly.
I did but I'm looking for cases closer to what we have. The field isn't used in any assets in Marketo and gets data from SFDC as sales fills it in.
Maketo docs say that things will go horribly wrong and we should just export and re-import data after the change. Easy enough but I'm looking for real world examples of what people have experienced.
Also, in Marketo the field is a Float and in SFDC it's a Text Area (255). Essentially we're changing it in SFDC because we want to be able to track ranges of numbers, which the text area field doesn't allow us to do.
When you change field type on SFDC side, I am not sure Marketo will even change it's type. I have tested some changes that did not reflect in Marketo.
When you change the type in Marketo between 2 compatible types (for instance from Currency to Number), I have not observed data loss. But sincerely, I would always backup my data before trying this.
I think you're correct. The current sync is between a Float and Text Area field. It appears to be working. I don't foresee an issue if the Text Area field switches to a number field in SFDC since a number can still be synced into the Float field in Marketo.
Testing this later today. I will update.
Do not use Float fields in Marketo -- period.
Whatever you're doing, step back and tell us about the values you're storing.