No. Devices connected to the iMac's other ports will still only be accessible by the iMac, not by the connected MacBook.
You can approximate some of the functionality you might get from this by using various software solutions to share your iMac's devices - such as sharing drives over the network, or sharing the mouse and keyboard using Synergy, etc.
S.M.A.R.T is a monitoring system for HDD and SSD implemented in the firmware of a drive using two different standards: ATA and SCSI.
SMART data is usually written to a special service part of the platter/flash storage unit.
All modern interface standards and the underlying protocols (SCSI, FireWire, USB – with USB-(S)ATA-Bridges, eSATA, Thunderbolt, SAS) are basically capable of transmitting SMART-data.
SMART data is not actively transmitted to hosts, but has to be queried by the host-OS, applications or drivers.
Depending on the OS, the SMART application, the drivers and the build-in hardware the success of those queries may vary broadly. BTW to retrieve SMART data from external USB/FireWire-drives attached to Macs use this kext driver (compatibility list).
As a result Target Disk Mode doesn't 'bypass' SMART at all, because SMART is implemented in the hard disk. It's hard to say in general if operating systems (or application and drivers) are locking out failing disks based on SMART data.
I doubt that at all because
- SMART isn't very reliable
- the implemented attributes varies between manufacturers and hard drive models
- the meanings and interpretations of the attributes and their values varies between manufacturers
At least i don't know of any such OS or application.
It's rather the OS in conjunction with the firmware and the (failing) hard disk itself which 'lockout' a device.
Best Answer
Only FireWire and Thunderbolt support Target Disk Mode.
You have to remove the internal disk and put it in an external case with UltraATA interface.
Alternatively you may create a bootable thumb drive (MacOS 9.1 or better), boot from it and create an image of your HDD with
Disk Copy
and save it to a network share. Building a bootable thumb drive and booting from it may take a while though because of the low bandwidth of USB1.1 (12 MBit/sec ≈ max. 1MByte/s).According to this article Mac OS X 10.3.9 - the latest Mac OS X which supports the G3 - unfortunately doesn't provide USB-booting: