SPE function to update the data template of an item (and optionally it's child items) from one template to another

Change-Template.ps1

<#
    .SYNOPSIS
        Updates the data template of an item (and optionally it's child items) from one template to another 
    .PARAMETER RootItemId
        Specifies an Item Id to start searching for items from     
    .PARAMETER SourceTemplateId
        Specifies the Id of the template to match items on (the template you wish to change)  
    .PARAMETER TargetTemplateId
        Specifies the Id of the template to change items to        
    .PARAMETER Recurse
        Specifies if all the child items below RootItemId should be included in the search.     
    .EXAMPLE
       Change-Template -RootItemId 36584658-7B62-4572-932E-8214A3CD7CE8 -SourceTemplateId 92C1C171-3ED0-4E8F-860A-FEAF14336A96 -TargetTemplateId DD68EBBB-4D82-411C-BA19-D95A65AAEF83 -Recurse $true 
       Updates the data templates of all items and childitems from one template to another
#>

function Change-Template{
    [CmdletBinding()]
	param(
    	[ValidateNotNullOrEmpty()]
    	[string]$RootItemId = "",
    	[ValidateNotNullOrEmpty()]
    	[string]$SourceTemplateId ="",
    	[ValidateNotNullOrEmpty()]
    	[string]$TargetTemplateId = "",
    	[bool]$Recurse = $false
    )
    
    $rootItem =  Get-Item -Path master: -ID $RootItemId;
    $sourceTemplate = Get-Item -Path master: -ID $SourceTemplateId;
    $targetTemplate = Get-Item -Path master: -ID $TargetTemplateId;
    
    Write-Host "Updating Templates for child items of '$($rootItem.Name)' from '$($sourceTemplate.Name)' to '$($targetTemplate.Name)'"
    
    $itemCount = 0;
    
    Get-ChildItem $rootItem.FullPath -Recurse:$Recurse | Where-Object { $_.TemplateName -eq $sourceTemplate.Name} | ForEach-Object {
        Set-ItemTemplate -Item $_ -TemplateItem $targetTemplate
        $itemCount +=1;
    }
    
    Write-Host "Completed Updating '$($itemCount)' Items"
}