The 1911 is the way to go.
The SP101 is a five shot gun. 5 shot revolvers are a touch difficult on the IDPA reload agendas. I've done it just for grins but not for a beginner.
Similarly, the 238 is not optimal for the competitive aspect but it would be fun to shoot as practice if it is a carry gun. I have a friend that shot one very well - but he is a very skilled IDPA shooter.
Also, shooting a 1911 is good practice for tap, rack and bang - ha, ha - ducking for cover.
