This question is asked about travel in India as there may be useful specifics I can learn. It will probably also be useful elsewhere. Notes at the end explain my general circumstances.
I intend to travel in India for several weeks, using long distance public services (train, bus, aeroplane) on a number of occasions. On a number of occasions I will be staying in relatively downmarket accommodation - usually single rooms in cheaper hotels. Probably not dorms but this is possible.
Indian rail suggests that the property lockers in AC class compartments will keep my goods secure. I've heard otherwise. Any advice?
How liable are goods in low cost hotel rooms to be at risk? What degree of security is needed for reasonable peace of mind?
I read that luggage lockers are provided at major railway stations. Are these reliably secure?
If I need to sleep in a publicly accessible area (eg dorm or room of uncertain security) I'd planned to have a highly intrusion resistant main bag (mesh or kevlar) attached to me with sensible sized stainless wire. How necessary is this or how substantial do I need such precautions to be?
Security could be inobtrusive or purposefully obvious. (eg stainless wire grid inside bag or outside. "Protected by ..." labels or none. Inobvious systems may be attacked with some damage even if unsuccessful. Obvious systems advertise valuable contents.
I will be alone and be carrying about 15kg of equipment - backpack and possibly a lightweight 2 wheeled trolley which I can "tow" with a belt attachment - looks silly but allows less body loading, far better hand access to camera etc. This can be secured in use against opportunist theft (thin stainless link with QR coupling) and converts to a carried load in seconds when required.
I'll have one main bag, about 15kg of gear. Main valuables apart from passport & money etc are laptop, camera system (batteries, memory, backup, lenses).
VERY large bolt cutter will defeat any cable I'm liable to want to use. (I've seen what doesn't work for bicycles in Amsterdam!). If unattended and noise is not an issue an angle grinder will make short work of almost any padlock and cable system.
I'm well travelled generally and used to pickpockets and keeping attached to my pack - but from what I read India can be challenging. Any long distance land travel that I've done (e.g. China) security of bag has not been a major issue, and I'm used to hotels where I am fairly sure my goods are safe. (I have a tamper-evident storage system that I use in uncertain hotel situations. This gives me confidence that goods have not been tampered with and dissuades "investigations" by cleaning staff. It will not stop anyone who wishes to look through my gear and does not care that I know that they have done so.
I'm contemplating an electronic alarm and COULD even carry a motion detect camera system with hidden camera BUT time and weight and sense suggests this may not happen).