Partial Panel. That's a difference. Also, holds with and without the ability to use an autopilot. NDB approaches.
Like many, I learned steam and transitioned to glass some time later. Not a problem if you're reasonably tech-savvy and have experience with moving map GPS units (especially the 430).
The main thing I'd say is that--if you're working on your IR G1000, don't switch back to steam gauges until you're done. An important part of instrument proficiency is being able to react and program reasonably quickly in a busy flight environment, so it's key for everything to be where you expect it to be. If you aren't already familiar with using an autopilot from your PPL training, get comfortable with it now (your 172s have the K(r)AP 140, I presume?).
Once you've got your IR ticket, go up with an instructor a couple times in steam gauge planes and do a mock IPC before you go flying into clouds in an older plane.