G'day Jim
I'm a pretty big fan of Loomis rods in general ...... but its the blank technology that is the key to Loomis rods ........ Their range is phenomenal & something will suit most applications
To answer your question
Yes there is a significant & very noticeable difference as you progress through the range (GL2/3 , IMX , GLX refer to the blank used)
GL2 is the entry level ( Graphite) .. Its lower modulus & a bit heavier GL2 is more robust ( stands up to a lot of abuse) ........ I think they are a little stiff
GL3 is a good choice ...... higher modulus graphite , lighter weight & more responsive ( still pretty tough) ....... Really good rods at a reasonable price. I like GL3 in medium Baitcasters
IMX .... Is high tech graphite technology ...... very light & sensitive ! .....more suited to the experienced fishoe ( quite fragile ..... & easily broken with bad technique)
Then you have a series of rods that are based on blends of glass & various graphite to give certain characteristics for specialised styles or to change the action. They usually have a name like Crankbait series , spinnerbait , mosseyback etc The dropshot rods are popular with SP anglers .......... There are some nice rods in this group of glass / graphite blends.
Then the Top of the tree ( GLX) ..... which is arguably the best blank material ( very light & super responsive ) ...... You look at these rods & its hard to believe the power rating ......... Once again a rod for the more experienced!
Taking into account what you intend to use the rod for ..... I'd go a GL3 ! I own a CR722 (GL3) which I use for my wild barra & jack fishing ..... Its a favorite of mine ( like a comfortable pair of shoes)
While there are lots of good rods on the market ...... I've just found the blank quality & range hard to go past.
The only real downside , is the cost ...... however just like what you are doing ...... I buy my Loomis rods out of the states ( & then you are talking unbeatable $ value) .
So give the GL3 a wirl ( not sure if there is a CR724 in GL3 ) ......
I hope this gives you some idea ..... PM me if you need a little help
Cheers
Nagg