Your can find some info on straight axle vs IRS here:
https://www.triketalk.com/forum/thre...-straight-axle
As far as which one is better than the other is definitely a matter of YOUR opinion. Need to ride several brands and the Tri Glide to make a inform decision. Take your time and don't rush, like all things its a big investment.
Secondly, there is a lot of information on this form, just do a search for your question.
Ride Safe
Nuc