the biggest con i usually see is the liability for the mse walls as well as perhaps the fact that the preliminary geotech/lab testing and construction materials testing adds up quickly which is usually not disclosed by the designer on the front end. the designers (not all) often write the plans and specs so that all the liability falls back solely on the owner (or to the owner's engineers somehow). the wall designer must be responsible for the design and acceptance of all materials used as well as the construction itself. the project geotech should not be responsible for the design...they are responsible for performing the sampling/testing as specified by the designer. once all that is squared away by both the wall designer and geotech, the mse walls are a great option since they offer more flexibility for difficult sites (notice 'flexibility' corresponds with 'movement'...the walls 'move' so keep that in mind). the design must include sufficient drainage and account for the materials onsite (foundation, backfill, etc). unfortunately, a lot of geotechs don't even realize the liability they accept by not challenging the plans/specs language. the language usually try to put the responsibility on the geotech to provide soil parameters (which are then interpretted by the designer as "design parameters" to punch in to a $400 program), settlement analysis, stability analysis, creep analysis, bearing pressure, materials conformancy, tests required, testing frequency, etc etc etc. but much like with cast in place walls, the designer must specify the testing required as well as testing frequency otherwise the geotech may take on the designer's liability. if the geotech is going to take on all the designer's liability, it would be better that the geotech design it themselves. if the geotech wants to take that burden, then that's on their shoulders but these walls are expensive to replace when they go horizontal and hit the ground (or even just have so much movement that whatevers sitting on top/behind experiences problems). to summarize, in part of the country, the wall "designs" are typically a cookbook recipe spit out for every site even though the onsite materials don't satisfy the design theory in many different aspects. then the owner is left trying to make his site fit the wall "design"...it should be the other way around. the mse wall/slope should be designed for the actual site conditions. out of hundreds of sites, i've never actually seen the wall designed for the site soils at the onset of the project. this is where the massive amount of disclaiming language comes in to play. some designers will make exceptions for out of spec materials but the disclaimers are still thrown out there. the owner and potentially geotech simply don't realize the liability they take on and unfortunately, there is usually not a working relationship between the different fields (even though they are both geotechnical fields).
the movement i've seen over the past couple years that i think is most appropriate is to make the wall design, construction and testing part of a single package so that all the liability falls with the designer to provide a product that works for the site. the owner often has their own geotechnical testing firm provide periodic secondary testing as comparison testing only and this testing is merely to help the owner sleep at night. in other words, the secondary testing not intended to be part of the formal testing for the wall certification by the designer. and if the wall designer specifies x testing at y frequency, then their package should play by the same rules and follow the same protocol.
cast-in-place doesn't have nearly the issues. drainage must be provided but not nearly to the extent of mse structures. once the foundation is prepared, you pour it and eventually backfill with compacted/tested material then move on. the biggest problem with these is that if the walls are tall (above the original ground surface) or if the underlying soils are highly compressible, differential settlement could be an issue and has to be designed for. but with a qualified geotech on board, this can be overcome but it will cost money. even with the additional costs, i've seen some architects/engineers require cast in place due to the massive headaches often involved with mse walls/slopes. for small to moderate sized walls, i like concrete. for massive walls or crossing swales where settlement will be issues, i like mse structures (assuming the above mentioned items can be resolved by all parties).
Msucog's advice is good, concerning the choice between MSE walls and cast in place walls. However, I read the question differently, and believed the OP was asking about using cast in place concrete for facing of MSE walls. That is not an option because of the movement of the earth mass. Use precast panels.
If the finished facing panels are to be attached to an MSE wall, the panels need to have flexibility to move when the MSE wall settles. Go with medium to smaller size precast panels, or just use a segmental block facing.
