The Point is : THERE IS A REASON , why the 4.5 Gen Typhoon, Rafale , Mirages and Gripens , The Famous, Delta daggers And My fav Jet : Pure Interceptor, Avro Arrow , The Most Advanced Jet of 50s are/were ALL DELTA.
Period.
Now carry on, .. Mine is better than Yours.. !
Yes, there is a reason.. and with that reason.. all the jets except the Mirages are canard coupled deltas that aim to avoid the pitfalls that the Tejas faces currently. I dont think bringing in "advanced jets of the 50's" is a good idea to come up with an example.
However your example with the Arrow is both ironic and befitting.. since both it and the Tejas suffer bring being excellent platforms plagued by either poor management or a poor customer.
Your points are pertinent for a traditional "naked" delta with no canards or compound geometry (which is effectively a canard attached to a delta for tejas) due to the excessive drag caused by flow separation in high alpha (and hence also high STR) regimes. So quite true for the mirage series and Mig 21.
However with the addition of canards and compound geometries like in the Eurofighter, Gripen and Tejas etc.., this issue has been mitigated quite considerably through flow direct re-energisation and/or higher spanwise flow from the greater incidence angle. The exact specs given their maximum STR is therefore something we cannot automatically to be inferior to regular conventional layouts...while they keep their superior ITR parameters because of their relatively lower wing loading (ceterus paribus). The exact trade-offs and balances are of course quite hush hush, high quality turn performance data is only really released for aircraft that have already been retired or are currently/close to ending their service lives.
Maybe in my free time I will attempt to do some CFD modelling using the geometries of canards and compound deltas as opposed to regular simple deltas so we can all have some layman data as to what the possible improvements might entail in rough % terms.....since gaining access to this online is quite difficult from what I have seen.
The compound geometry is NOT a canard attached to a delta. The compound delta is an attempt to solve the drag issue generated as shown in your figure by creating an energized vortex that allows for better manoeuvrability at supersonic speeds.
Also, the exact trade-offs are not "HUSH HUSH". Over 50 research papers can be found on the effects of various delta designs and especially the compound delta used on the Tejas which is also present on the 1960's Saab Viggen.