I had figured that the inconsistent handling between addresses with only decimal digits was just an unfortunate cost of PowerShell, until I saw the AddressTransformation... so I poked at it a bit more:
> Read-DbgMemory -Address 0x17409680
17409680 "."
> 0x17409680 | Read-DbgMemory
Read-DbgMemory : Could not access memory: 90108800
At line:1 char:14
+ 0x17409680 | Read-DbgMemory
+ ~~~~~~~~~~~~~~
+ CategoryInfo : ReadError: (15301904384:UInt64) [Read-DbgMemory], DbgMemoryAccessException
+ FullyQualifiedErrorId : MemoryAccessFailure,MS.Dbg.Commands.ReadDbgMemoryCommand
> Read-DbgMemory -Address 17409680
Read-DbgMemory : Could not access memory: 0109a690
At line:1 char:1
+ Read-DbgMemory -Address 17409680
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : ReadError: (17409680:UInt64) [Read-DbgMemory], DbgMemoryAccessException
+ FullyQualifiedErrorId : MemoryAccessFailure,MS.Dbg.Commands.ReadDbgMemoryCommand