I have SimCommander fairly well configured for DCS (GS-5, G-Belt, SimVibe w/ 4 Mini-BK), however there still appear to be a few glaring holes in the software when it comes to Flight Sims (I fly DCS 95% of the time with a little bit of MSFS too). Overall the GS-5/G-Belt/SimVibe combo is currently very good, but I believe it will be truly excellent when the remaining features that are needed are implemented in SimCommander. As far as barrel rolls and climbing, currently I find the G-Seat to be very good, with the G-Belt lacking quite a bit (not because of its potential, but because of software limitations). SimVibe is IMO great for immersion overall.
There three main improvements I'd like to see. Let me caveat these up-front with the statement that these are just my impressions based on my own experience and attempt to configure things. Maybe I don't understand the software, maybe I'm making mistakes in configuration or interpretation. Take it with a pinch of salt, and know that I understand that software development is hard and DCS may not be the easiest game to support.
1) Conditional Effect Groups for DCS
Currently there is no way to trigger a conditional effects group based on DCS telemetry conditions. That means I've had to reach a compromise on effects like 'road texture' and 'road bumps'. These effects are amazing on the ground, but when you're in the air they still trigger when turning which makes the air feel 'grainy' and strongly detracts from the flight experience. Some kind of 'radar altitude' parameter needs to be exported so that we can have strong road texture/bump effects when radAlt == 0, and nothing otherwise. This would allow us the best feedback when taxiing, taking off and landing, and a nice smooth experience during flight. Currently I have to tone these down to a level which is too weak on the ground, and present enough to be distracting in the air.
Additionally it would be nice to have a condition for the pilot 'in cockpit' or 'ejected', and ideally for telemetry to take into account events like ejection and so on.
2) Proper G-Belt support for DCS.
Currently 'Roll' seems broken. It increases strap pressure with roll angle in one direction only. If you bank right (based on your settings) the pressure increases, but nothing on rolling left. It doesn't really make sense to me, I've never found a way to properly set it up. One imagines you want one strap to tighten and one to loosen based on angular acceleration in the roll axis.
Differential / fine-grained support for negative and positive vertical G. I've requested this previously, but we need to be able to tune the vertical G response differently in positive and negative regimes. Personally I would want the G-Belts in the mid position at zero G, fully relaxed at +9.3G where I'm being crushed into my seat and my shoulder straps should feel loose, and fully tight at -3G where I'm being lifted out of my sit and the straps should be biting into my shoulders.
Overall the G-Belt is the area I feel is currently weakest. To be honest I don't get much out of it because it just doesn't seem to respond to DCS telemetry in a sensible way, and I can't get it to do what I think it should do in particular flight manoeuvres. I haven't found a way to improve that through SimCommander so it's currently just sort of toned down to doing nothing much at all. Perhaps this is due to my own failure to configure it well, but factors such as those I've listed certainly would help. I do feel that it could be amazing if the G-Belt software was tailored more towards DCS.
3) General improvements to DCS telemetry feedback.
This one is a bit nebulous but there are some effects where I don't really feel that the game telemetry is having any real effect. A specific example would be some of the engine vibration effects that depend on RPM. As far as I can make out I am correctly scaling the effect to the RPM exported by DCS, but the effect does not seem to change with the RPM of the engine when playing. Again, this could be my own failure to configure it properly, but I've tried quite a few experiments and drawn the conclusion that the responsible telemetry is either not being exported by DCS and/or not being listened to or acted on by SimCommander.
If there's interest I could export and share my profile.