Yes, I must confess that I mixed it w/ Stay & Stayinfo, but this is only valid in Europe. I used it a few times and never had any problems w/ ATC.

As said in here:

The use of Item 15 and STAY provides the ability to indicate a vertical deviation during the course of the activity.

OK, may be I twisted their arms a bit. 

So I will refrain from doing it during my flights in UK.

There would possibly be some administrative risks in using it, such as ATC/FIS closing your flight plan when you don’t want them to on landing at an intermediate airport, a particular state not permitting its use for landing, or if you decide to land and stop longer than the planned period and needing to close the plan to stop overdue action being taken at destination. 

sorry for the lengthily & mixed issues posting. I would like to rise the following practical issues, which prevent me using the current SD FPL handling. Microlights are more & more common, and as far as performance is concerned, they meanwhile outperform ancient Cessnas. Flying intl. is no problem anymore for modern micros. As far as FPLs are concerned, I wish:

1) A departure button for departing from uncontrolled fields, as already in a separate forum topic

2) The possibility to create a bunch of FPLs in advance and store/edit them in SD, before being actually submitted to ATC, as part of vacation flight planning, which might be a bit difficult, once underway.  Spilt store vs. submit.

3) Microlights have limited fuel on board, due to weight limitations. Currently SD blocks FPLs exceeding the max. endurance w/ one max fuel. However end2end FPLs foresee the possibility of refueling underway using the /DLE feature. Submitting such an FPL w/ /DLE might be the easy choice for crossing borders w/ a short stop, just for refueling and/or border crossing. I would appreciate, if SD could take into account the FPL /DLE feature for not to block the submission of an FPL, if the total flight time exceeds the 1 petrol tank endurance. I think a warning would be good enough, rather than blocking. Pilots should know...

Best Regards