I doubt the wisdom of company mortars.
I understand that platoon mortars ("commando" mortars) make a lot of sense (albeit 40mm MV is a good substitute) and battalion mortars (usually 120 mm) are very useful as well (especially if the larger calibre makes use of munition types which are not nearly as practical in 81.4 mm calibre).

Some reasons against Coy mortars:

(1) Company-level mortars burden the company leader with leading one more element (even though it's not necessarily marching separately).

(2) By range and field of fire company mortars are often (though not necessarily) not available for supporting other companies. This leads to lesser personnel efficiency than for Bn mortars.

(3) Company mortars need to be close to the infantry in contact and are less capable than Bn mortars to use shoot & scoot tactics for survival.

(4) Three batteries of Coy mortars are inevitably a greater ammunition resupply mess than two batteries of Bn mortars.

(5) Coy mortar batteries are hardly capable of carrying a satisfactory quantity of ammunition (more than 3 kg per 81.4 mm shot!) unless they employ pack animals, vehicles or porters (none of which is usually done, and all is more troublesome at the Coy level than Bn level).

(6) Radio calls for fire support are about as easily done to a Bn battery as to a Coy battery.

(7) Coy and Bn mortars often co-exist, and typically so in different calibres (81.4/82 and 120 mm). This de-standardises ammunition supply and adds to the logistical mess.

(8) Infantry-centric forces would often operate in a manner which keeps the Bn compact enough for centralised fire support. Bn mortar batteries could be split and dispersed to the companies during exceptions.

(9) Splitting Bn mortar fire support into three Coy mortar platoons and a Bn-level mortar unit also splits up the mortar employment competence. A more centralised mortar unit (mortar Coy at Bn level) allows for easier establishment and maintenance of a fine proficiency.

(10) Self-defence and 24/7 360° security is much easier done and much more affordable personnel-wise if the mortar personnel is more centralised.

(11) More emphasis on Bn-level mortars allows for more large calibre weapons (98 or 120 mm), and thus for more firepower that's helpful against difficult targets (AFVs, penetration of roofs).