If I could do it again, I would do Horizon Hxr instead of the Sport SX, with a GPS400W. By the time you add the arinc adapter needed for the sport, the costs are close, plus you get much more IFR functionality with the HXr. Add a GRT mini or similar for redundancy.

Chris

No, wrong question. IFR is serious business. The correct question is, “How much redundancy is needed for you to feel safe?” Obviously this is a subjective question, and requires some knowledge of how various boxes work, and what their failure modes are. e.g., I have an SL30 VOR/ILS, and a Dynon D4 with internal battery, that I have never used, except for practice. But they are there, just in case...

Note added: The OP mentioned training. For that he’ll need to be able to do some non-gps approach, unless he finds an accomodating examiner. Also, what will you gps only guys do if your sole gps box goes down? Or worse, someone jams the signal, or you just happen to get bad geometry (this recently happened to me)?

I've heard that a few times, and I've thought about it even though it doesn't apply to the bird I'm presently flying. En route and in the soup I would ask for no-gyro vectors to VFR (that's predicated on having a VFR out which is one of my personal minimums). If you're talking about failure of the box, I'd use whatever VFR GPS I had onboard (for the OP the the GRT box; for me, ForeFlight) to help me even with the vectors. If that's not feasible, ask for a radar approach option. There are probably a couple more things one could do.

If some ne'er-do-well jams the system that's a bad day but again I go back to having a VFR out. Sure, if you're on an approach while that happens you're in for a bad time. But even if I had a ground based backup, am I going to reconfigure for an ILS midway down the approach or try and run the ILS missed? Nah. I'm going to ask for a vector.

I guess, to me, it's no different than back when you only had a VOR approach and worried about the VOR going out of service. Or you had one navcomm and in the panel.

There's only so many cascading errors I'm willing to worry about. I run the hazard analysis and look at probability of failure and decide what is going to keep me up at night. I'd fly with a GTN 625 (plus VFR backup) and a comm radio only.

If looking for a less expensive SL30, I *think* that the VAL Com2000 paired with the Nav2000 is supposed to give you SL30 functionality & interface capability, in the same vertical space. Don't take my word for it though; give them a call if that solution interests you.

If I'd known about it earlier, I'd likely have bought those instead of the used non-WAAS 430. I'm not yet rated ( :-) ), and getting rated seems less and less likely, so the 430 was a questionable investment for me.

edit: Just saw their remote mount comm & nav for flat screen panels, too.

Charlie
https://www.valavionics.com/products.html

I have plans similar to the OP. The instructor I plan to use said the minimum he and the examiner can work with is an SL30. I have a single EFIS so he requested some backups. I have a GRT Sport and will likely install a GRT Mini as the backup.

Rather than install a SL30 I went with a MGL V16 and will add a N16 when the time comes. Also, the Sport and Mini are compatible with the GNC300XL so I might install one since they are so cheap and I can do the install.

I had the same plan until a couple of weeks ago when my instructor pointed out that you have to do 3 different types of approaches for the checkride - tough to do without a GPS and NAV radios. There are multiple types of non-GPS approaches, but it becomes problematic finding one you can actually access. Not impossible, but I went ahead and added a GNC420 to my stack.

Most people can find a VOR, LOC, and ILS approaches somewhere nearby. They count as three. Unfortunately, GPS-WAAS only gives you two. Non-WAAS, one.

For those comparing the SL-30 to the VAL nav, there is one important difference:
The SL30 can bring in two VORs, or an ILS and a VOR, simultaneously. As MB and LOMs disappear, more and more ILS's now use a VOR cross-fix for the FAF, step downs, etc. My SL30 displays, on my GRT HX, the primary ILS (or VOR) on the HSI needle, and the second VOR as an RMI needle - making the approach with just one nav easy. With the VAL you'll be constantly swapping frequencies back and forth to find that fix, while tracking inbound.

The MGL N16 has the same capability as the SL30 which I why I decided I'd give it a try. I've only installed the V16 but will add the N16 in the near future.

I'm lucky in that my home airport has ILS, LOC, and VOR approaches. Until recently it also had a NDB approach.

Approaches
 

I only have a GTN 625 in my plane. I do have multiple portable back ups. So no Nav. I did all my training in my plane and took a check ride in it also. Examiner had me do 2 gps LPV approaches and one LNAV approach. He said the LPV approaches down to 200 AGL are essentially the same as precision ILS approach. You just need to find an examiner that will do this.

I thought that's what my first thirteen words said?