First, I'll admit my limitations, I have spend a lot of effort on US stuff, but only a modest effort at the Germans, so I won't critique the German vehicles.
Iwo Jima Sherman (which I believe was the same casting used for the Battle of the Bulge?) - generally represents an M4A3 75mm Wet Stowage. Biggest single problem is that suspension. Note that the return rollers should only be on trailiing arms, the extra roller on a forward arm is bogus. One problem is that BMC and others copied the exact error leading to a number of innaccurate Shermans around. Without taking a Dremel tool and resculpting the suspension the problem can't be fixed. Next is a minor irritation that comes partly from the Tamiya model company - the extra "patch" armor on the side (called applique armor) should not be present on this model of Sherman. This was a factory level fix to earlier hulls to add protection to ammo racks, in the later M4A3 depicted the ammo racks had been relocated to the bottom of the hull, so the patches wouldn't help. The hull should be exactly like DD45. Andy got the hull and suspension right on that one. Trivia - many of the M4A3s on Iwo Jima had been field modified by the Marines with wooded planks spaced about 4" off the main hull side and the space between the steel and the wood was often filled with concrete - the Japanese never had enough good AT guns but they had lots of dedicated soldiers willing to run up and put a mine against the side of a Marine tank. 'nother trivia - Andy did add the water tank on the rear deck that was unique to USMC tanks in the Pacific. The infantry often ran short of water on hot islands and some units' tanks carried a 50 gal. tank of drinking water for the gyrenes to fill canteens from.
Personally, I have taken a BMC Sherman (based on the K&C Iwo Jima Sherman) and combined it with the suspension and turret from an FoV M4A3 to get a 54mm version of this very common late tank. I can provide photos on request.
On DD27 we have an interesting mix of features. The vehicle produced as actually an M4A1 76mm Wet Stowage, HVSS, (informally an M4A1E8). The features are better here. The HVSS referes to the wider "easy eight" suspension that went from the earlier 16-inch wide tracks to about 23" wide. (Wider track = lower ground pressure, ergo better mobility). The tank is really quite good. Minor problems - Andy used a model of an Israeli Super Sherman for his master and a few of the stowage items are unique to those tanks, and there is no photographic record of the M4A1E8 having seen combat. It's "sister" the M4A3E8 saw lots of action from the Ardennes campaign through Korea, it has the welded hull and a Ford engine versus the cast "turtle" hull and Radial engine of the M4A1 series. There were (reportedly) a number of M4A1E8 in Europe ready for issue but the war ended before anybody used one in anger. After VE day a lot of them were given to the French Army and many ended up in Israel. (for movie buffs, those are French M4A1E8s in several of the scenes in "The Longest Day", including the fight at the Uistreham casino). So I still have my DD27 in the collection because it still makes a good late war Sherman and the crew figures are VERY nice.
Again, as a Sherman buff I enjoy DD45. It's an M4A3 with 105mm howitzer. These were issued to tank battalion headquarters elements to give the commander his own direct fire HE capability. This same hull was also used for a 76mm gun turret (like DD27) or a 75mm gun.
I hope these comments have helped a little.