good thinking to stick with one powder and get things figured out. when you start changing stuff, make sure to change only one thing at a time. smokeless can be picky and finicky, but once you get the hang of it you'll wonder why you didn't do this years ago!
lil gun is no longer a recomended powder and for a good reason
you mentioned a few other powders you might try eventually,which will be more addicting than you may expect. one thing to caution is that with H4198 you will be above 2200fps, if you are in that range then you may experience misfires especially in cold, ie hunting conditions. with using 4198 i think your shoulder will be the limit of how fast you want to shoot..