I have had both a Guide Gun and a 22" Sporter in .45-70.
The 22" barrel gets higher marks for both accuracy and performance - but not by much, as the're very close.
Close enough, that it's a matter of handling both to see which floats your boat better.
I've actually gotten to the point where I prefer, and carry, the 22" Sporter most often.
Although the Guide Gun was very appealing at first blush, I soon wanted some undefineable thing "more".