I am a gifted dyslexic and was not diagnosed until college - by my TA no less! So I have always been very concerned about the hidden compensation affect of being gifted - but things changed over time with DS now 6.5 which makes waiting not such a bad thing, although there are things I would recommend - if you haven't already gotten this advice already - get all the other testing done first - vision and OT. Turns out DS has mild vision issues which ironically impact primarily his ability to do the timed tests on WISC and puzzles. He was such a snail but eventually did it, he just had to work so much harder at it. And he they found a few other oddities. But between 5 and 6 he has stopped reversing his numbers - although when tired sometimes the 5 is backwards again. So that seems age developmentally appropriate. But his writing is still a mess - its huge, and he makes bizarre spelling and punctuation mistakes which he does not do when speaking. This is being remediated by the school OT and his words are now more legible and the use of spacing more appropriate. But his teacher has recommended they start keyboard training with him - I thought we would have to fight for this, so happy they have suggested it. He will be doing both typing and writing homework, basically they have recognized that he can't get his ideas down as effectively due to the writing issues. But we are But there might still be some dyslexia aspects - but it is not affecting his reading which is his strength so its impossible to tell.
So I would suggest getting vision, OT and that stuff done if you haven't, and waiting for the Eides next year or you could get WPSSI testing now and wait until 6 to see the Eides so they could do the WISC. For me it was when it began to affect him that prompted action, and that was when his writing was clearly far behind in PK. But we didn't get a good fit with the OT so we didn't stick with it and then in K we went through the school system. The OT told us that getting them in K is what they prefer because when they get them by 3rd grade its tougher to remediate.
DeHe