gable end dry verge systems

Just wondering if anyone has any experience of dry verge systems for gable ends? The guy who installed our pvc facias and gutters last year is trying to convince me that I should replace the concrete under the tiles at the gable with this new pvc dry verge system that fits over the edge tiles and locks locks them in place. He says it prevents wind blowing the tiles off and/ or water getting in through cracked concrete under the tiles.
It would be great to hear from anyone who knows about this as I haven't a clue. I'm concerned that it may be an unnecessary extra.
Thanks

sales pitch IMO

Thanks for the reply. He did a good job (at least I don't see any issues to date) on the PVC gutter replacements and a neighbour in the estate did vouch for the work he did for her. However he's quite pushy on the sales pitch side of things and he does do that "we're in your area" line.

Have any of your tiles ever blown off? It would want to be one hell of a gust of wind to dislodge them if they are interlocking concrete tiles.

So if no tiles have blown off in however long you have had the house, do you reckon you need this system?

Hi Thanks for the advice on the concrete tiles. The tiles have stayed put without extra help until now. I decided not to go with it in the end. He was quoting 250 euros but I decided that it was an extra expense I could do without. Thanks for your advice on this.

As awfulpest implies, "If it ain't broke, don't fix it.