It actually stands up pretty well against the Aegis, at least the early version of the Aegis.
Against the early Aegis, circa 2372, the two are roughly comparable. They share the same thrust profile, 2/3. The armor is comparable, with the Dart only having a few points less overall than the Aegis, but that is because it is using 1194tons of Standard Armor to the 627tons of Ferro-Carbide of the Aegis. In terms of firepower, the advantage goes to the Aegis in terms of overall firepower, being able to bring more concentrated fire to bear upon targets. However, the guns of the Aegis circa 2372 are much lighter than they will be after refits towards 2750. The majority of the firepower for the 2372 Aegis comes in the form of NAC10 batteries, with the Nose, Fore Arcs, and Aft each having a quad-turret, the Broadsides each having a pair of quintuple turrets, and the Aft Arcs having a single sextuplet turret each. These are supplemented by NL55s, NL45s, and White Shark launchers. In comparison, the Dart's firepower is the 4 Killer Whale Launchers in the Nose supplemented by pair of NL45s and NAC20s, the Fore Arcs having a pair of NL35 and a pair of NAC25s, the Broadsides having a pair of Nac30s and a pair of LNPPCs, the Aft Arcs and Aft being copies of the Fores Arcs. For heat dissipation the Dart wins out with nearly a 30% increase over the Aegis. The Dart has greater fuel bunkerage, 8975tons vs the 1000tons of the Aegis. In terms of cargo the Dart also has an advantage with roughly an additional 12000tons over the Aegis. For Dropship and ASF capacity, the Dart carries 6 Dropships to the Aegis' 4 but the Aegis can carry 18 ASF and 10 Small Craft to the Dart's ability to carry only 6 Small Craft.
Circa 2372, the Dart and Aegis can go head-to-head with it being a toss-up as to who comes out on top. The Dart can win if it uses its heavier weapons in the Nose to great effect. The Aegis can win if it can use its larger amount of weapons to score more hits and pile on the damage faster. When their supporting craft come in to play the advantage can swing towards the Dart given its ability to bring 6 Dropships to the field to the Aegis' 4. While the Aegis can carry more integral ASF the ability to bring 2 more Dropships can negate that as it gives the Dart greater potential with a more potent mix of Carrier and Assault ships.
By 2722 the Dart had been largely retired from SLDF and Great House service any outside this had been destroyed; the exception in this case being the RWR which kept a few hidden away to be used in the Amaris Coup later. However, at the time the Dart was disappearing in favor of the Avatar, the Aegis was getting new life breathed into it. by 2750 the Aegis had undergone refits to bring it up to a more "modern" standard.
The 2750 Aegis kept the same level of armor, but improved its heat dissipation and weaponry while also adding in a LF Battery. The 2046 heatsinks of the Aegis were upgraded to Doubles bringing its heat dissipation to just under 10% of what the Dart is capable of. Where the 2750 Aegis really shines thought is in firepower. The NAC10s are replaced with the Nose and Fore Arcs each get a pair of NAC35s, the Broadsides two double NAC35 turrets and two triple NAC20 turrets, the Aft Arcs get two triple NAC20 turrets, and the Aft gets two double NAC35 turrets. This gives a much heavier overall punch than the old NAC10 mounts. At the same time the White Shark Launchers are only retained in the Fore Arcs and AFT while those of the Broadsides and Aft Arcs are replaced with Barracuda launchers. A slight downgrade, but the ability of the Barracuda to better target ASF and Small Craft makes up for it somewhat. All of these refits, particularly the inclusion of the LF Battery, drop the cargo capacity of the Aegis from 128440tons to 85835tons.
Compared to the Dart, the 2750 Aegis refits make the previous toss up turn to be more in the favor of the Aegis. The Dart still has a chance, if it can keep fighting at long range, where the NAC35s can't be used, but as soon as the Aegis closes distance to medium range the damage potential swings decidedly in favor of the Aegis.
Other contemporaries of the Dart are: the Commonwealth-class cruisers of House Steiner, the Wagon Wheel-class frigate of the Taurian Concordat, the Winchester-class cruiser of the Taurian Concordat, the Riga I-class frigate of the Terran Hegemony & SLDF, and the Black Lion I-class battlecruiser of the Terran Hegemony & SLDF. Compared to these, well it is a mixed result. They are all slightly better than the Dart in at least one or two ways, so in a fight the Dart would either be evenly matched or at a slight disadvantage. Facing these contemporaries, plus the newer ships coming online towards the end of the 200-year lifespan of the Dart spelled its end. After 2722 the only user of the class was the RWR which kept at least one secretly in service, the RWS Conquistador, using it to attack the shipyards over Mars at the start of the Amaris Coup and where it was subsequently destroyed by concentrated attacks by two squadrons of Model 96 Elephant-class Dropships of the SLDF's 23rd Wing (The Little Beavers) which were also destroyed in the exchange. It is implied that the RWR may have had more than one Dart secretly in service at the time of the Amaris Coup, but only the RWS Conquistador is actually named and given details as to its use and fate.