While the images of the LAV III 155mm SPH do look tantalizing, I think that the Caesar would be superior.
First off, the cost of the Caesar would probably be far less than a LAV III mounted SPH.
Next, the actual gun on the Caesar has a superior range compared to that on the LAV.
The proposed gun on the LAV is a modified XM77 Light Weight Howitzer. This weapon is 39 calibre and has a max. range of 24, 700 metres with conventional rounds and 30, 000 with rocket assisted rounds.
The Caesar has a max. range of 42, 000 metres with conventional ammo.
The XM77 would have been a far superior choice of weapon for the 105mm howitzer equipped RCA units to have been equipped with rather than upgrading an overly obsolete system.
I personally think that a mix of XM77's, Caesars and HIMARS would be an ideal force for the CF's.
Here in the Marine Corps, the 14th Marine Regiment (4th Marine Divisions artillery regiment) is to have 2 battalions (Canadian regt. equiv) equipped with all the Marine Corps HIMARS. Incidentally the 14th Marines and 4th Marine Division are all reserve forces.
Given the nature of HIMARS employment as counter-battery fire for use against an opponent with significant artillery assets, such as Iraq during the Gulf War, or any future major conflict (in which reserve call-ups would be likely) it makes sense to have the HIMARS tasked to reserve units.
Training for a HIMARS role could be very easily done by reserve units. Gun Drills are Gun Drills...doesn't take very long to become too proficient or keep in practice...especially with technology making things easier.