If you've already got it, it's worth a try (for £66). The synsg is a clone of the Diana 34, but you may find the finishing of parts inferior. Barrels can be a bit hit and miss (excuse the pun). I have an xs20 (a HW95 clone) and whilst it was a good rifle to shoot (I bought it pre-tuned from Lyn Lewington the V Mach technician), the barrel let it down on accuracy past 20yds. Being a clone, I purchased a .177 HW95 barrel and quite frankly you will struggle to differentiate firing cycle from my SFS tuned HW95 (also in .177). I also have an smk xs19 in the cabinet and with a welsh will tuning it's shoots very nicely (but needed a trigger upgrade from new, the Gamo 440 and it's clones are pretty notorious for this). I've consistently hit a 40mmx40mm knockdown with the '19 at 75yds at a spring air rifle 'bash', so not all barrels are bad - just some.
Hope you have some success with it. If not, Edgar Bros are now Diana agents and you will get some keen pricing on a the full range, but if it's FAC you want, the mod 52 (now that will do 24fpe+) might be the answer.