That's debatable, swashplate antenna presents its own problems. Added weight and maintenance overhead due to hydraulics required for mechanical steering.
The second is increased RCS, one of the biggest RCS contributors is the radar antenna, the amount of scattering caused by the antenna can be reduced by canting the antenna outward by 15 degrees. The idea is to scatter the incident electromagnetic waves away from probing radars. If the AESA antenna is mounted on a gimbal or swashplate and mechanically steered then the antenna will present a 90 degree angle to enemy radars - this is generally undesirable. Bandstop and bandpass filters that reduce the amount of scattering requires the antenna to remain fixed in the radome (nose cone).
Both AESAs are of different type, so the advantages & drawbacks are also different.
In fixed AESA, at extreme scan angles the effective aperture decreases, and the performance of the radar (range, sensitivity and jamming resistance) declines as a result. M-Scan has a larger field of regard than a fixed AESA, and better performance at the edge of the scan envelope.
The performance-degradation issues encountered in fixed-array AESA radars is well known. Fixed-array AESA technology suffers performance losses at wide-scan angles. To fix this USAF had plan of using 'side-arrays' on F-22 but it was dropped due to the associated expenses.
EADS & Saab believes that, increase in both air to air and air to ground capability far outweighs any minimal increase in maintenance. The Swashplate AESA allows repositioning and to counter performance degradation at high off-bore-sight angles.
The swashplate employs a "repositioner" driven by electric motors to negate the problem limited scan, along with providing other benefits. Antenna movement is automated using software to optimize radar performance relative to the tasks. It is not exactly "rotating" AESA but re-positing radar with pre-calculated movement.
In the air-to-air arena, the ability to move the angled array gives advantages in beyond-visual-range missile engagement, allowing the so-called F-pole to be maximized.
The gimbal of a pointable AESA does not have to be anything like as fast as an M-Scan gimbal.
The high-speed stuff, tracking a moving target, is still done electronically, with the gimbal moving relatively slowly to optimize the field of view.To do this, it's essential to have a radar that can continue to track the target and guide the missile as the shooter turns away.
This is important for any MRCA today as the whole system - in the air-to-air regime - is influenced by air-combat simulations in which a fighter-to-fighter engagement could involve multiple MRAAM shots, followed by a supersonic turn to evade the adversary's fire and extend the F-pole.
Most fighters scan around 60 degrees off the nose but the Swashplate AESA can provide twice as much of the conventional. One tactical application, among many: the fighter can launch a datalink-updated missile and then turn sharply away, avoiding the adversary's return shot while its own missile continues to guide.
The limited scan angle problem was also understood during JSF development. But JSF being able to fly with VLO benefited and another idea was that "the wide scan update" would be provided to F35 via B2s & other datalinks. Although the emergence of wide-scanning fighters in post-2020 scenario is known to JSF developers.
Now employing Swashplate re-positioning AESA on EFT or Gripen NG will bring some RCS compromises. But these MRCA are not primarily VLO or stealth fighters. So it is fair & highly efficient.
