1, Do not write thread titles with all capital letters - it makes you look like a douchebag and possibly decrease amount of people who will visit your thread to give you an advice. ;)
2, Setting PT samples to 1024 is a nonsense, as you will get almost no antialiasing. What you have read is probably to set PT samples in !HDcache! to 1024. It was a big mistake that two settings were named the same, and it will fixed in next version. :)
3, Your materials look crappy because you used converter, instead of redoing them from scratch and learning how CoronaMTL works. Converter is just an aid tool for people who know what they are doing and need to convert some scenes. But it never works 100% without manual clean up. So if you are new to Corona, then avoid converter and do materials from scratch.
4, Why do you put lights in windows? Corona environment lighting is nearly as fast and accurate, Just put your environment map into environment slot. Just put your HDRI into environment slot, that is absolutely all.
5, Physical camera is already added and will be available with next public alpha. It will not be adjustable during rendering though.
6, Your scene is slow because you do not know what you are doing. If you were new to Vray, you would end up the same.
Most common mistake is glass with refraction set to solid mode. You have to use hybrid glass. Solid means everything behind glass surface is computed as caustics, so if you put solid glass in window, you will seriously slow down your scene. We admit that refraction modes are really badly named and create a LOT of confusion, so we already fixed it for next public alpha version.
Another very common mistake is too high albedo. Fresh mountain snow is about RGB 230 white... arch of white paper is 220, and white walls are usually around 200-210. People often have 250 or even 255 white on their walls and wonder why their scene converges so slowly.
Next common mistake is changing max. sample intensity from it's default value. It will give you some additional accuracy, but may radically slow down your render.
7, VFB+ is really great, so if you have bought it, then stick with it ;) There is only one developer of Corona, Ondra, and while he can do some VFB improvements, he will never be able to do as perfect framebuffer as a person, who can spend all of the time programming just VFB.
Here is a simple guide which if you follow, you will almost always get a fast and clean result:
1, Make a new empty scene, switch renderer to Corona, and keep everything at default except setting secondary GI to HDcache
2, Merge contents of your scene into this new scene, but do not merge lights, merge everything except lights. Daylight system is a group, so if you have that, and merge it with other stuff, just make sure to delete it.
3, Create new CoronaMTL with default settings, and assign it to ALL objects in the scene.
4, Select all object, open object properties, and make sure there are no fakes enabled, such as disabled camera visibility, or disabled shadows. Fakes in Corona, if used unwisely, may actually lower performance.
5, Go through the scene, and hide large glass objects, that would occlude a lot of scene surface from lights. That means glass planes in windows and glass walls or glass railing sections. You do not need to hide small stuff, like glasses on the table, chandeliers, or small glass statues.
6, Open your environment dialog, click the map slot, add bitmap, and load your HDRI or even low dynamic range environment map.
7, Do a test render, you should have nicely lit render with gray material. Now it is time to adjust exposure settings, and possibly rotate your environment map to get the lighting you want.
8, Add artificial lights, like cove lights or light bulbs in your scene. Add them one by one, and observe if any of them creates noise that is going away a lot slower than other lights. If that is the case, then go take a look what is wrong with the light. It may be intersecting something, be oriented in wrong direction, or something like that. Try to not use directionality feature as it is not very optimized at the moment. IES are also a bit slower than regular lights, so use them only when you really need them.
9, Once you have all the lights added, and tweaked to your lighting, start to add materials one by one. Start with a white wall for example, and make sure you do not create superbright materials as i mentioned above. I usually do not go over RGB 210. If i have a texture that contains pure white color, i just change output value in bitmap to something like 0.8-0.9.
10, Now that you have all your materials and lights done. Create a new material, make it a glass (reflection and refraction IOR at 1.52 and reflection and refraction level at 1), and set refraction mode to hybrid. Now unhide all those large glass objects you have hidden previously, and apply this material to them.
11, Tadaaaa, you should have fast and optimized scene! :)
Seriously, if you follow this guide, there is a very few things that could go wrong.