You'll only need frontal access if you did a poor job of planning in the first place. To me, there is nothing worse than frontal access. Frontal access:
1) completely ruins the picture on a wall look.....assumimg that's what you're trying to acheive
2) it usually allows light bleed into the viewing room.
3) it allows more tank noise to enter the viewing room
4) most large, high end wall tanks are accompanied by nice highly finished viewing rooms that will now be subject to water drips. There is no way that I would risk damaging my imported wool carpet or teak hardwoods to accidental saltwater messes or additional humidity.
As for the usual complaints....it just means that not enough planning went into the project. The most common ones are:
1) I can't see into the tank without turning everything off.....
I use an acrylic viewing plate that floats on the surface... this allows for perfect viewing....even photography....even on the choppiest of surfaces. The panels are just little 8 inch square boxes.
2) I can't clean the colored rear panel......
I have a clear rear panel that has a thin colored panel that presses up against it. This allows me to just slide out the colored panel for easy cleaning or viewing from the rear....and, I can change the background color if I ever choose to.
3) the lights are in the way......
The lights must be designed to easily be removed from the tank top. Lights are the number one item that can limit access if not properly thought through.
4) I can't see how I'm placing corals.......
This is a somewhat legitimate complaint; but, with the acrylic viewing boxes, you'll get used to it and I find it to really to be no problem.
5) I can't clean the front panel.....
I use a magnet for everyday cleaning. I also can clean any coralline from the rear by using my little viewing boxes again. From the rear... looking into the tank, the front panel will be like a mirror and very easy to see what I'm cleaning. I also use a nylon scrapper that my tank manufacture gave me. It is slightly softer than the acrylic....so it can't scratch the acrylic. The key, though, is don't let corraline build up in the first place. It's easier to run the magnets once everyday as you pass by than scrape for hours because you let the coralline build up.
If properly designed, the rear access only aquarium will have better and more efficient access than the frontal access. If you design a "frontal access" tank for a "rear access" tank....you're just asking for disappointment. Big tanks are not merely bigger small tanks.....the design should be completely different. It seems that lately there have been several big tanks that were designed like a small tank on steroids.
I spent alot of time thinking about maintenance and access before I set up my big tank. I tried to think of all the nuisance problems that I had with smaller tanks and how to solve those problems. Everything was designed around easy access and easy maintenance.......without it.....big tanks become a big pain.