I think the right tool for the job must be the reciprocating Allsaw. Any disk-type saw will cough up loads of dust unless it has a water cooling jet, making the job messy and unpleasant. Cut off saws cannot cut internal corners in an opening, so another tool would be required to make good.
A low-dust saw with reciprocating action is a much more pleasant tool to use, and is much less tiring to use, and I would say safer.
Used with a general purpose blades, the Allsaw will also be more accurate and less likely to run away with an inexperienced user on a vertical cut through the wall, and is lighter to use for horizontal cuts or excavation of horizontal mortar beds than disk cutting tools.
The blades cut to a depth of about 110mm - so a single skin of bricks at a time. There can be access problems cutting near to internal corners on brickwork, but that applies to both types of saw.
A low-dust saw with reciprocating action is a much more pleasant tool to use, and is much less tiring to use, and I would say safer.
Used with a general purpose blades, the Allsaw will also be more accurate and less likely to run away with an inexperienced user on a vertical cut through the wall, and is lighter to use for horizontal cuts or excavation of horizontal mortar beds than disk cutting tools.
The blades cut to a depth of about 110mm - so a single skin of bricks at a time. There can be access problems cutting near to internal corners on brickwork, but that applies to both types of saw.