Access conditions and plasma performance of H-modes with acceptable ELM size (extrapolated to ITER conditions) have been one of the main research lines in recent experimental campaigns at JET. Earlier experiments were dedicated to the study of the pedestal and ELM behaviour of high density/high confinement ELMy H-modes. These experiments focussed on the exploration of the effects of the plasma edge magnetic geometry (triangularity d, as well as proximity to double null, or quasi double null plasmas, QDN) and of q95 on the pedestal parameters, edge stability and ELM size. In Single Null (SN) configuration at high d and modest values of the safety factor (q95~3-3.6), the plasma pedestal accesses a regime of reduced Type I ELM frequency, and enhanced inter-ELM losses, named the mixed Type I-II regime. In this regime, H98~1 and n/nGr ~0.9 are obtained routinely. In Asdex-Upgrade, steady state Type II ELM H-modes at high confinement and density (H98~0.95, n/nGr~0.85) are obtained in QDN plasmas, at bN~1.8 and a minimum q95~4. Attempts to reproduce this regime by modification of the magnetic configuration (from SN to QDN) and by varying the edge safety factor up to 4.5 in high shaped plasmas at medium plasma current (2.0 to 2.5MA) were not successful, leading to reduced plasma confinement and eventually to a transition to Type III ELMy H-mode regimes This paper presents the results of new experiments carried out to further investigate the physics of small ELMs in JET. These experiments explored two main directions: the first had the aim to further investigate the role of QDN in JET to reproduce the Asdex-U Type II regime, by making a dimensionless identity with a Type II ELMy H-mode of Asdex-U. The second line of investigation was to study the effect of bp on the pedestal MHD stability, in analogy with results from JT-60U, where "grassy ELMs" spontaneously replace Type I ELMs in H-modes, when bp>1.7, in high d plasmas with q95>4.