I think if they believed there was a serious safety issue with the Kenda tires, they would have done something about them by now.
Well I can tell you about a serious safety issue and it relates to the OP's question directly because I did change out my tyres at 350(ish) miles, the distance from my dealer to my home. I already knew about the issue because this is my second RT machine and my partner also is on RT number 2.
I've no idea where you ride or the type of roads you are riding but I can understand that if you primarily ride the slab you may never come across the issue.
The issue is related to the tyre structure and the way it deforms and is present to some extent in most tyres (possibly all tyres), but it's very marked in the front OEM tyres. It has caused the RT to veer completely into the adjoining carriageway more than once and fairly frequently pulls the RT over the road centre line.
I'm referring to the tendency for the tyre to ride up a longitudinal ridge as its shoulder makes contact with that ridge edge. It's exacerbated by flexibility in the steering tie rods but it's cause lies in the tyre. Here in the UK roads are often surfaced by applying tar to one side of the carriageway and covering the tar with stone chippings then the other side of the road is surfaced in the same manner. This leaves a raised section some inches wide, and occasionally more than a foot wide, in the centre of the carriageway because it receives two coatings there. On top of this there is usually the road centre line which adds to the thickness of the raised portion.
When the tyre is run in contact along this edge it distorts and jumps over the raised edge putting the wheel across onto the opposite carriageway. Normally this isn't a serious issue because it can quickly be countered so it's just a nuisance, also, staying to one's own side of the centre road marking is the normal way of travelling but, if you should cut it fine or need to avoid a road hazard then the outcome can be serious. I've only described one situation where the problem can arise but plainly this tyre behaviour can occur anywhere the road surface is poor. If the surface is such that the tyre jumps over an edge and it finds successive edges due to road surface irregularities then the bike can be many feet off line in an instant! Don't ask me how I know!
You might think that you'd be able to counter this but you can't do much about it since, 1) it's not particularly turning the steering, it's a tyre distortion issue and 2) it's very fast.
I mentioned the flexibility of the tie rods and this is to some extent part of the issue too; when the tyre distorts by rolling up a road imperfection at its edge, it becomes slightly conical as its edge lifts and a cone will roll in a circle so the tyre applies a turning moment to the road wheel and loads the tie rod, because the tie rod is flexible it allows the road wheel to be veered by the tyre a little and prevents some measure of counteracting force applied by the rider to attempt to correct the bike running off course. Now this brings us to a modification which will help mitigate the tyre issue and also sharpen up the steering response noticeably. The OEM tie rods on the 1330 Spyders are made from aluminium and although they are more rigid than the previous V-twin Spyders they are still flexible and bend under steering loads. The tie rods on our Spyders are made from 1" stainless steel tube with spherical bearings instead of the poor, and variable, quality of the standard tie rod ends. These tie rods allow much better control of the wheels and tyres but they are not a full solution.
So, in conclusion, my choice is to select a road tyre which has very little sensitivity to road surface imperfections and control the wheels with good tie rods. Hence why I changed out my tyres at new. As an aside, it also removes much of the twitchy tendency the Spyder has over any road surface which is less than good.
IMHO, of course...
To the OP; the choice is yours, only you know how and where you're going to ride your Spyder. Other than the issue I've given above, I think the OEM tyre is fine with good wet and dry grip but with limited traction on loose surfaces or winter conditions. Particularly the rear tyre.