"Are they easy to handle and work with?"

That depends on your application. Typically, concave aberration corrected gratings are used for flat field spectrometers. Since these gratings combine dispersive and imaging optics with low astigmatism, coma and field curvature, such spectrometers usually posess the easiest possible setup: an entrance slit, the grating and a CCD/CMOS detector. Their assambly however requires some alignment.

"Any comparison with plane reflection gratings in terms of temperature stability,"

I don't think that there should be a huge difference. It depends on the substrate and coating materials (concave gratings on Zerodur should be available) and dimensions. If your application comprises high temperatures >60°C, resin replica gratings might be unsuitable and you have to use more expansive master gratings.

"efficiency,"

Concave, aberration corrected gratings are to my best knowledge always manufactured holographically. In literature, it is often stated that holographic (plane and concave) gratings are inferiour to ruled plane gratings regarding efficiency, since blazed profiles are more difficultly achieved. However, I can't confirm this: blazed gratings can indeed be holographically manufactured with nice profiles and hence blazed efficiency behaviour, so no big difference, when it's done correctly.

"ghosts"

If the holographic setup for mastering was optimized in terms of stray light, there can be literally no ghosts orders and overall least possible scatter (grass). Holographic gratings should always be superiour to ruled gratings, if the recording setup was good.

Thanks Felix for such a detailed answer. Am more confident about placing an order for these gratings. 

Do you have any (inexpensive) vendor in mind for these gratings? Edmund sells for whopping 550$+(150$ delivery in India) !

There are different suppliers for holographic gratings, e.g. Richardson, Horiba Jobin Yvonne, Shimadzu. My company Zeiss also has holographic concave aberration corrected gratings with different parameters in stock, see here (polychromator): http://applications.zeiss.com/C1257E4D00444CAE/0/C0716D83B2383CBDC1257E5300351E93/$FILE/gratings_portfolio_E_Monitor_CZS.pdf

Unfortunately the prices are not mentioned, but I suppose that the order of magnitude you have to pay shoud be equal for all suppliers. By the way I assume that edmund only sells gratings from another manufacturer from the ones mentioned above.

Yeah, price is an issue. Would there be a tremendous difference in quality if I try a Chinese manufacturer? One of them quoted me 135$ without shipping.