Hi Lance,
I have an IFR rating as of August 2007, a Maule MX7-180c with Garmin 430, non ifr 250, STEC 50 with GPSS.
The STEC 50 with GPSS is great. I had some initial problems in that the 430 had to be reconfigured before GPSS would work. Make sure it is all working before you get too far from the avionics shop.
Aside from practicing some approaches/holds in low level stratus for currency, I have only used my IFR rating to fly out of Half Moon Bay when the fog rolled in during lunch which is the limit of my comfort because:
My 430 has gone dead twice, once staying dead until taken to the avionics shop for No Trouble Found. My AI has failed and been replaced, my DG has failed and been replaced, my CDI has failed and been replaced. Everything was new as of 2006 and my prop is dynamically balanced. The first time the 430 failed was a rainy night when I was just maintaining night currency. All the other failures were in VMC. The AI was a great failure: it wouldn't erect. The DG was obnoxious: it would suddenly shift (not precess) a large (more than 30) number of degrees (I'm lucky to have a witness, because I have trouble believing that description myself). GPS and ILS would drive the CDI fine, but VOR wouldn't.
My next planned future purchase is a Garmin SL-30 (pulling out the Garmin 250) and another CDI with glideslope. Then I might begin to believe I had redundancy and might begin considering flying in stratus clouds to a destination. Only after that, would I consider upgrading to WAAS, even assuming I had the money.
I'd keep the KX-155 with glideslope.
In terms of rain events, I ventured out for the first time last month into an area of scattered showers/isolated thunderstorms. Just as lightning strikes and virga appeared at 12 o'clock we made a 45 degree turn to our destination; the storm didn't move while we had lunch. We had no intention of going into clouds; in the air, we'd turn around; on the ground, we'd wait. Having done it once on purpose is enough for me.
I used the King training course to prep for the written and got the written out of the way before proceeeding to flight training. I don't know whether you have looked at
http://www.overtheairwaves.com/, IFR Refresher, and IFR Magazine. I enjoy them and they do keep making me ask the question: am I proficient enough to fly IFR?
Good luck,
Dick